Final Pavement Report CO FLAP ALA Lane 6 North_04-22-2021.pdf

FINAL PAVEMENT REPORT

CO FLAP ALA 6(1), LANE 6 NORTH

GREAT SAND DUNES NATIONAL PARK

ALAMOSA COUNTY, COLORADO

RockSol Project No. 636.01

April 16, 2021

Prepared for:

Jacobs Engineering

Attention: James Mills, PE Project Manager – Transportation Design

9191 South Jamaica Street Englewood, CO 80112

Prepared by:

RockSol Consulting Group, Inc.

12076 Grant Street Thornton, Colorado 80241

(303)962-9300

CO FLAP ALA 6(1), LANE 6 NORTH RockSol Project No. 636.01 Final Pavement Report April 16, 2021

Table of Contents

1.0 PURPOSE AND SCOPE OF STUDY

1.1 Purpose of Work

1.2 Scope of Work

2.0 PROPOSED CONSTRUCTION

3.0 SITE CONDITIONS AND GEOLOGIC SETTING

3.1 Climate and Terrain

3.2 Geology

4.0 PAVEMENT CONDITIONS

4.1 Summary of Existing Conditions

5.0 SUBSURFACE INVESTIGATION

5.1 Field Exploration

5.2 Laboratory Testing

6.0 SUBSURFACE CONDITIONS

6.1 Pavement and Base Course

6.2 Subgrade Soils

6.2.1 Soil Maps

6.2.2 Penetration Resistance

6.2.3 Classification

6.2.4 Chemical Properties

6.2.5 Corrosion Properties of On-site Soils

6.2.6 Swell / Consolidation

6.2.7 Resistance “R” Values

6.2.8 Proctor Values

7.0 PAVEMENT DESIGN RECOMMENDATIONS

7.1 Pavement History

7.2 Design Traffic Volume

7.3 Structural Section

7.3.1 Milepost 0.0 to 4.0 and Milepost 8.0 to 16.0

7.3.2 Milepost 4.0 to 8.0

7.4 Hot Asphalt Concrete Pavement Mix and Binder

8.0 GEOTECHNICAL RECOMMENDATIONS

8.1 Earthwork Design

8.1.1 General Grading

8.1.2 Reuse of On-site Soil

8.1.3 Subgrade Preparation

8.1.4 Graded Slope Design

9.0 LIMITATIONS

List of Figures

Figure 1 Project Location (Google Maps)

Figure 2 Geologic Setting (USGS)

List of Tables

Table A Summary of Existing Surface Condition

Table 1 Segment 1 - Deep Patches

Table 2 Segment 2 - Deep Patches

Table 2 Continued Segment 2 - Deep Patches Table 3 Segment 3 – Deep Patches

Table 4 Summary of Existing Pavement and Aggregate Base Course Thickness

Table 5 Summary of Soil Type per Pavement Segment

Table 6 Requirements to Protect Against Damage to Concrete by Sulfate Attack from External Sources of Sulfate

Table 7 Guidelines for Selection of Corrosion Resistance Levels

Table 8 Corrosion Resistance Lab Testing Results

Table 9 Minimum Pipe Thickness for Metal Pipes Based on the Resistivity and pH of the Adjacent Soil

Table 10 R-Value Summary

Table 11 Proctor Test Results Table 12 Vehicle Class Distribution

List of Appendices

Borehole Location Plan .............................................................................................................. A

Borehole Logs ............................................................................................................................ B

Pavement Photos and Core Logs .............................................................................................. C

Summary of Laboratory Test Results ......................................................................................... D

Soil Type Map ............................................................................................................................ E

ESAL Calculations and 1993 AGDPS Output ............................................................................. F

PMED Output ............................................................................................................................ G

FDR – Cement Laboratory Design ............................................................................................ H

Preliminary Pavement Memo ....................................................................................................... I

1.0 PURPOSE AND SCOPE OF STUDY

RockSol is a subconsultant to Jacobs Engineering Group, Inc. (Jacobs) for the initial design phase to 30% for the proposed improvement on Lane 6 North in Alamosa County, Colorado by conducting geotechnical analysis for pavement design for the Federal Highway Administration, Central Federal Lands Highway Division (CFLHD) as part of the Federal Lands Access Program.

This report and recommendations herein were developed in accordance with our Scope of Work (SOW) dated September 1, 2020.

1.1 Purpose of Work

Lane 6 North is an east to west 16-mile-long two-lane Alamosa County route that starts at State Highway 17 to the west and ends at State Highway 150 to the east. Lane 6 North is in Alamosa County and provides access to state and federal areas including Great Sand Dunes National Park and Preserve, San Luis Lakes State Park, Zapata Falls, Bureau of Land Management (BLM), and Forest Service.

The purpose of this project is to develop full pavement rehabilitation treatment for 16 miles of two-lane road in keeping with the initial CFL Vetting construction cost estimate used to establish project budget. The initial Vetting estimate was based on assumed treatment by pulverizing and hot asphalt concrete pavement (HACP) overlay with areas of subexcavation repairs. Viable rehabilitation treatment alternatives will be evaluated and presented.

Select areas were identified during on-site field assessment. The extent of these areas will be evaluated and will be addressed in the final report through localized subexcavation, stabilization or other treatment to address existing localized subgrade and pavement failures.

1.2 Scope of Work

The scope of work includes the following:

• Field investigation to collect pavement cores and subgrade borings (Completed Nov. 4, 2020)

• Laboratory testing of soil samples collected from borings (Completed Dec. 2020)

• Preliminary Pavement Recommendations Technical Memo (Dated December 31, 2020)

• Draft Pavement Report

• Final Pavement Report

2.0 PROPOSED CONSTRUCTION

The initial preliminary approach for this project is to pulverize and widen the roadway to a standard 24-foot width and overlay with a 3” asphalt pavement. A fiber optic conduit may be added along the entire 16-mile route with intentions for hook up to the Great Sand Dunes National Park. The project site is located north of Alamosa, Colorado and southwest of Great Sand Dunes National Park. Lane 6 North connects State Highway 17 to the west to State Highway 150 to the east as shown in Figure 1.

Figure 1. Project Location (Google Maps)

3.0 SITE CONDITIONS AND GEOLOGIC SETTING

3.1 Climate and Terrain

Climate data posted by usclimatedata.com from the weather station in Alamosa, Colorado reports the highest average monthly precipitation in August at 1.27 inches and the lowest average monthly precipitation in January and February at 0.26 inches. Average monthly precipitation in November, when geotechnical exploration was performed is 0.42 inches.

Lane 6 North is located in the San Luis Valley which is part of the Rio Grande River Basin. Water tends to flow east to west. San Luis Lakes State Wildlife Area contains natural lakes and is directly north of Lane 6 North at approximate Milepost 8. The surrounding area has generally flat to mildly sloping terrain.

3.2 Geology

Geologic maps from the United States Geological Survey (USGS) were used to identify the geologic features underlying Lane 6 North. The western portion of the roadway (approximate MP 0 through MP 7) is underlain by the Alamosa and Santa Fe formations (QTsf) which primarily consist of alluvial fan deposits and pediment gravels, stream deposits, and volcanic debris. Eolian sand (Qdpd) with fixed parabolic dunes of accumulation are mapped at the surface from approximate mile posts 7 through 12. Eolian sand with longitudinal dunes (Qdl) is mapped east of MP 12 with alluvial fans (Qaf) mapped at the Lane 6 North and SH 150 intersection. A geologic map of the area is shown in Figure 2.

Project Location

SH 17

SH 150

Figure 2. Geologic Setting (USGS)

4.0 PAVEMENT CONDITIONS

RockSol met in the field with the Alamosa County Road and Bridge Director and staff to view existing problem areas, repair locations and materials, and historic drainage and construction methods. The County Staff noted that standing water is common along Lane 6 North from County Road 113 (CR 113) to the east for four to six months each year. This is generally the segment from MP 4.5 to MP 9.2. The overall terrain is virtually flat with little or no directional flow in the north-south direction across Lane 6 North, and minimal locations with sufficient gradient for parallel ditch flow. The County mentioned that the initial roadway embankment was constructed by excavating material from the adjacent ditch areas to build up and compact into the current finished roadway embankment, generally to a height of no more than two feet above the adjacent excavated ditch lines. The existing embankment material appears to consistently represent the adjacent soils consisting of very fine water and wind-deposited silt and sand.

In locations of recurring localized pavement structural failures, the County staff has reportedly sawcut the pavement, removed underlying material to a depth of five to six feet, placed woven geotextile on the subgrade and backfilled with local pit-run material of rock diameter up to six inches. Aggregate base course and three inches of asphalt pavement were reportedly placed to finish each patch repair. These patches were typically only partial lane width and six to ten feet along the roadway for the local extent of each failed pavement segment. These deep patches were not extended out to intersect the adjacent embankment side slope. County staff described numerous such patches completed over the last two years starting at CR 113 and continuing to the east until the general location of the irrigation ditch crossing. In locations where numerous patches were constructed in close proximity, the County followed the patch construction with full lane-width asphalt pavement overlay of approximately 1.5-inch thickness. Many of the underlying patches are evident from reflection cracks in the overlay along each deep patch perimeter.

Lane 6 North SH 150

QTsf

Qdpd

Qdb Qsf

For this project, RockSol has divided the Lane 6 North alignment into 6 segments. Each segment was separated based on the pavement thickness, documented pavement distresses, or subgrade soils. The following is a brief synopsis of the roadway condition and dimensions for each segment based on our October 20, 2020 site visit.

Table A – Summary of Existing Pavement Surface Condition

Pavement Segment Number

Lane 6 North

Pavement Location

Width

Average Pavement Thickness

(in.)

Pavement Surface

Condition (Good/Fair/Poor)

1 Milepost 0.0 (at SH 17) to 4.5 (east of CR 113)

24’ 3.95 Poor

2 Milepost 4.5 to 9.2 (at canal) 24’

32’ (MP 8.9-9.2)

5.9 Poor

3 Milepost 9.2 to 12.0 24’

32’ (MP 9.2-9.4)

3.1 Poor

4 Milepost 12.0 to 12.6 24’ 6.5 Poor

5 Milepost 12.6 to 13.3 24’ 5.0 Fair 6 Milepost 13.3 to 16.1 (at SH 150) 24’ 3.2 Poor

Segment 1 - Milepost 0.0 (at SH 17) to 4.5 (east of CR 113):

The intersection of Lane 6 North with SH 17 from the SH 17 shoulder stripe line to 55 feet into Lane 6 has minimal distress and may be considered eligible for simple overlay to a milled-but joint at SH17. The remainder of this segment of Lane 6 North is considered in poor condition with moderate severity block cracking over 50 to 100% of the pavement surface, high severity shoulder edge cracking and deterioration over nearly 100% of the pavement, moderate severity depressed transverse thermal cracks at 10-foot average spacing, and low severity rutting of ¼-inch average over 20% of the pavement length. The pavement in this segment is 24’ wide.

Image 1- Intersection of SH 17 and Lane 6 North Looking Northwest

Image 1a – MP 0.1 Looking East

There are 4 deep patch areas constructed by the County in this segment:

Table 1 – Segment 1 Deep Patches Approximate

Milepost Direction Approximate Dimension Placement

3.39 WB 6’x6’ Right Wheelpath (WP)

3.61 WB 6’x12’ Right WP

3.82 WB 6’x6’ Right WP

4.47 WB 6’x6’ Right WP

Segment 2 - Milepost 4.5 to 9.2 (at canal):

This segment of Lane 6 North is considered in poor condition with moderate severity fatigue cracking over approximately 30% of the pavement area, high severity depressed transverse thermal cracks over 1” in width at 25-foot average spacing, and low severity rutting of ¼-inch average over 20% of the pavement length. Moderate severity fatigue cracking exists over 30% of the pavement but is highly variable with localized areas of high severity fatigue and rutting over 1” depth. County personnel mention that this segment of roadway exists in a low drainage area with numerous artesian wells and high ground water table as evidenced by white evaporite soil deposits and existing ponding areas immediately adjacent to the roadway throughout. The County staff report that 2020 was extremely dry, However, intermittent ponding and drying from adjacent artesian wells remain evident. This segment has the highest number of County-placed deep patch repairs.

The pavement from MP 4.5 to 8.9 is 24’ wide. The pavement width is 32’ from MP 8.9 to MP 9.2, with the first 1,200’ having gravel shoulder material placed on top of the underlying paved shoulders. There is one cattle guard at approximate MP 9.2.

Image 2 – Ponding and Evaporite Deposits MP 7.6 Looking South

Image 2a – MP 5.6 Looking East

Image 2b –Deep Patch Area Reflection Cracks Through County Overlay Area

There are at least 38 deep patch areas within this segment. Large machine patch areas were visually evaluated to locate reflection cracks from apparent underlying deep patch locations:

Table 2 – Segment 2 Deep Patches

Approximate Milepost

Direction (East or

Westbound)

Approximate Dimension Placement Details

4.62 WB 6’x6’ Right WP

4.68 WB 6’x6’ Right WP

4.79 to 4.82 WB and EB 24’x100’ Full Pavement Width This location appears to be full depth repair throughout

5.06 WB 6’x6’ Right WP

5.08 WB 6’x24’ Right WP

5.14 to 5.22 WB 12’x 380’ Full WB Lane This location was machine patched after multiple deep patch repairs (at least one 6’x12’ and one 6’x3’)

5.24 WB 6’x6’ Right WP

5.29 to 5.34 WB 12’x250’ Full WB Lane This location was machine patched after multiple deep patch repairs (at least one 6’x15’ and one 6’x12’)

5.38 WB 6’x6’ Right WP

5.42 to 5.48 WB and EB 24’x320’ Full Pavement Width This location was machine patched after multiple deep patch repairs (at least one EB 6’x12’, one EB 12’x12’, one WB 6’x9’, one WB 12’x24’)

5.49 EB 6’x6’ Right WP

5.60 EB 6’x6’ Right WP

5.63 EB 6’x6’ Right WP

5.64 WB 6’x6’ Right WP

Table 2 Continued – Segment 2 Deep Patches Approximate

Milepost Direction (East or

Westbound)

Approximate Dimension

Placement Details

5.66 WB 6’x6’ Right WP

5.74 EB 6’x6’ Right WP

5.94 to 5.97 EB 12’x130’ Full EB Lane This location was machine patched after multiple deep patch repairs (at least one 6’x15’ and one 6’x12’)

6.10 EB 6’x6’ Right WP

6.13 to 6.26 EB and WB 24’x700’ Full Pavement Width This location was machine patched after multiple deep patch repairs (at least one EB 6’x6’, one EB 6’x15’, three WB 6’x6’, one WB 6’x9’)

6.32 EB 6’x6’ Right WP

6.37 WB 6’x6’ Right WP

6.41 to 6.42 WB 12’x60’ Right WP

6.63 WB 12’x24’ Full WB Lane

6.76 to 6.78 WB 12’x75’ Full WB Lane

7.36 to 7.38 EB 12’x100’ Full EB Lane

7.8 to 7.81 WB 20’x25’ Full WB Lane

Segment 3 - Milepost 9.2 to 12.0:

This segment of Lane 6 North is considered in poor condition with low severity block cracking over 5% of the pavement surface, moderate severity shoulder edge cracking and deterioration over 50% of the pavement, moderate severity depressed transverse thermal cracks at 20-foot average spacing and ½” depression, low severity longitudinal joint centerline cracking over 100% of the pavement length, low severity rutting of ¼-inch average over 20% of the pavement length, and low severity fatigue cracking over 25% of the pavement occurring primarily in the westbound direction.

The pavement width is 32’ from MP 9.2 to MP 9.4, with the last 120’ having gravel shoulder material placed on top of the underlying paved 4’ wide shoulders. The pavement from MP 9.4 to

12.0 is 24’ wide.

Image 3 – MP 10.0 Looking West

There are 4 deep patch areas within this segment:

Table 3 – Segment 3 Deep Patches

Approximate Milepost

Direction (East or

Westbound)

Approximate Dimension

Placement

Details

10.12 EB 6’x6’ Right WP

10.32 WB 6’x6’ Right WP

11.70 WB 6’x6’ and 6’x30’ Right WP

Segment 4 and 6 - Milepost 12.0 to 12.6 and Milepost 13.3 to 16.1 (at SH150):

These two segments of Lane 6 North have very similar conditions and are separated by a 0.61-mile segment that was covered with an overlay and that is described in the next report section. At the intersection of Lane 6 North with SH 150 extending to 15 feet past the cattle guard, there exists minimal pavement distress and overlay to a milled-but joint at SH 150 may be considered.

The remainder of these two segments are considered in poor condition with moderate severity shoulder edge cracking and deterioration over 50% of the pavement, moderate to high severity transverse thermal cracks at 10-foot average spacing, low severity longitudinal joint centerline cracking over 100% of the pavement length, moderate severity rutting of variable ½-inch average depth over 70% of the pavement length, and moderate severity fatigue cracking over 70% of the pavement occurring both in the east and westbound directions. Pavement depressions have developed in fatigued areas over approximately 10% of the pavement length. There are no deep patch areas constructed by the County in this segment.

The pavement in these sections is 24’ wide. There is one cattle guard at approximate MP 14.8.

Image 4 – MP 15.0 Looking West

Image 5 – MP 16.1 Looking East at Intersection with SH 150

Segment 5 - Milepost 12.6 to 13.3:

This location appears to have received a full width overlay in roughly 2015. It is 3,215 feet in length. Pre-overlay photo imagery shows high severity fatigue and transverse cracking distress from approximate MP 12.63 to MP 12.69 and from MP 13.12 to MP 13.18 within this overlay area.

This segment of Lane 6 North is considered in fair condition with low severity pavement edge cracking over 5% of the length, low to moderate transverse thermal cracks that are reflecting from the underlying pavement and are becoming noticeably depressed throughout the typical 1” wide crack areas. This segment has improved aggregate shouldering material as placed during the overlay. The pavement in this section is 24’ wide. There is one cattle guard at approximate MP 13.3.

Image 6 – MP 13.0 Looking West

4.1 Summary of Existing Conditions

The existing condition of all Lane 6 North pavement segments is considered poor, except for the fair condition for the short overlay segment from MP 12.6 to MP 13.3. This segment shows reflection cracking from underlying pavement distress that is expected to rapidly progress into poor condition within two to three years. Age and traffic related structural failure is evident in all pavement segments. Major rehabilitation or full removal and reconstruction of new pavement structure will be necessary to ensure Lane 6 North pavements can perform to the required design life of 25 years.

5.0 SUBSURFACE INVESTIGATION

5.1 Field Exploration

Subsurface conditions were identified by RockSol with auger boreholes and penetration test sampling. Seventeen pavement boreholes were drilled approximately one mile apart and alternating lanes along the length of the roadway, labeled EB-1 through EB-9 and WB-1 through WB-8 and we obtained two pavement cores identified as C-1 and C-2. The pavement cores were taken for the purpose of determining total pavement thickness near the cattle guard approximately 30 feet west of the junction with SH 150. Ten additional boreholes were drilled at selected high distress and patch areas, labeled as B-1 through B-10. Field exploration was performed November 2nd through 4th, 2020. Specific locations of each borehole are presented in Appendix A, Borehole Location Plan.

Dakota Drilling, Inc. was the drilling contractor used to perform all geotechnical borings. Cores of the existing pavement were taken at each borehole location. A truck mounted CME-45 drill rig was used for advancing boreholes and soil sampling. The boreholes were advanced using 4 inch outside diameter solid stem augers to a maximum depth of approximately 5 feet to 10 feet below existing grades. The boreholes were logged in the field by a representative of RockSol at the time of drilling. The boreholes were backfilled at the completion of drilling and patched with asphalt patch material.

Subsurface materials were sampled and resistance of the soil to penetration of the sampler was performed using a modified California barrel and standard split spoon samplers. The modified California barrel sampler has an outside diameter of approximately 2.5 inches and an inside diameter of 2 inches. The standard split spoon sampler used had an outside diameter of 2 inches and an inside diameter of 1⅜-inches. Brass tube liners were used with the modified California barrel sampler to retain material from the sampling process.

Depths at which the samples were taken, the type of sampler used, and the blow counts that were obtained are shown on the Borehole Logs presented in Appendix B. Pavement core logs and photos can be found in Appendix C.

5.2 Laboratory Testing

Soil samples retrieved from the borehole locations were examined by the project geotechnical engineer in the RockSol laboratory. Selected samples were tested and classified according to the Unified Soil Classification System (USCS) and the American Association of State Highway and Transportation Officials (AASHTO). The following laboratory tests were performed in accordance with the American Society for Testing and Materials (ASTM), AASHTO, and current local practices:

• Natural Moisture Content (ASTM D 2216)

• Percent Passing No. 200 Sieve (ASTM D 1140)

• Liquid and Plastic Limits (ASTM D 4318)

• Dry Density (ASTM D 2937)

• Soil Classification (ASTM D 2487, ASTM D 2488, and AASHTO M 145)

• Gradation (ASTM D 6913)

• Standard/Modified Proctor Compaction (AASHTO T99/T180)

• Water-Soluble Sulfate Content (CDOT CP-L 2103)

• Water-Soluble Chloride Content (AASHTO T 291-91)

• Standard Test Method for pH of Soils (ASTM D 4972-01)

• Soil Resistivity (ASTM G 187 - Soil Box)

• Resistance R-Value and Expansion Pressure of Compacted Soils (AASHTO T 190)

Laboratory test results were used to characterize the engineering properties of the subsurface material. For soil classification, RockSol conducted sieve analyses and Atterberg Limits tests. Lab testing was also performed on selected samples to determine the water-soluble sulfate content of subsurface materials to assist with cement type recommendations. The Resistance Value (R- Value) tests were performed by Cesare, Inc. Water Soluble Chloride Ion Content tests and pH Tests were performed by Colorado Analytical Laboratories. All other laboratory tests were performed by RockSol. A summary of the laboratory test results is presented in Appendix D and are also on the Borehole Logs presented in Appendix B.

6.0 SUBSURFACE CONDITIONS

6.1 Pavement and Base Course

Asphalt pavement was located at the ground surface for each borehole and core location. Asphalt thickness ranged from 2.5 inches to 7.5 inches for the roadway pavement locations. Aggregate base course thickness encountered in Boreholes EB-2, EB-5 through 9, WB-2, WB-4, WB-5, and WB-8 ranged from 3.0 inches to 7.0 inches. A summary of existing pavement section and base course thicknesses encountered at each borehole location is presented in Table 4. Pavement section and base course thicknesses are also shown on the individual borehole logs in Appendix B. Photographs of pavement cores can be found in Appendix C.

Table 4 – Summary of Existing Pavement and Aggregate Base Course Thickness

Segment Borehole ID Location

Asphalt Pavement

Thickness (in)

ABC

Thickness

(in)

EB-1 Approx. MP 0.1 – EB Lane 3.75 7.5 WB-1 Approx. MP 1 – WB Lane 3.50 NE EB-2 Approx. MP 2 – EB Lane 2.50 5.5 WB-2 Approx. MP 3 – WB Lane 5.00 6.0 EB-3 Approx. MP 4 – EB Lane 4.25 NE

WB-3 Approx. MP 5 – WB Lane 4.00 NE B-10 Approx. MP 5.1 – WB Lane 6.0 NE B-8 Approx. MP 5.6 – WB Lane 5.0 NE B-9 Approx. MP 5.63 – WB Lane 6.0 NE B-7 Approx. MP 5.95 – EB Lane 6.5 NE

EB-4 Approx. MP 6 – EB Lane 5.50 NE B-5 Approx. MP 6.15 – WB Lane 5.5 NE B-6 Approx. MP 6.22 – WB Lane 6.5 NE B-4 Approx. MP 6.75 – WB Lane 7.0 NE

WB-4 Approx. MP 7 – WB Lane 6.50 4.0 B-3 Approx. MP 7.81 – WB Lane 7.5 NE

EB-5 Approx. MP 8 – EB Lane 5.50 4.0 WB-5 Approx. MP 9 – WB Lane 7.50 7.0

EB-6 Approx. MP 10 – EB Lane 2.75 3.0 WB-6 Approx. MP 11 – WB Lane 3.50 4.5 B-2 Approx. MP 11.75 – WB Lane 4.0 NE

4 EB-7 Approx. MP 12 – EB Lane 2.75 4.0

B-1 Approx. MP 12.74 – EB Lane 6.0 NE

WB-7 Approx. MP 13 – WB Lane 5.00 4.75 EB-8 Approx. MP 14 – EB Lane 2.75 3.0

WB-8 Approx. MP 15 – WB Lane 3.00 3.0 EB-9 Approx. MP 16 – EB Lane 2.75 2.25

N/A C-1 ~30’ W of SH-150 – W. Side of Cattle Guard 3.00 NM N/A C-2 ~20’ W of SH-150 – E. Side of Cattle Guard 5.00 NM

ABC = Aggregate Base Course; NE = Not Encountered; NM = Not Measured

6.2 Subgrade Soils

Subsurface conditions generally consisted of native and fill silty to clayey sand and sandy clay.

Bedrock was not encountered during auguring and sampling operations to the maximum depths explored, approximately 5 feet to 10 feet. Groundwater was encountered in 6 boreholes between MP 5.0 and MP 12.0 at depths ranging from 6 feet in Borehole B-10 to 9.5 feet in Borehole B-5.

Descriptions of the surface and subsurface conditions encountered in the boreholes are provided in this section and are also summarized on the Borehole Logs presented in Appendix B.

6.2.1 Soil Maps

Subgrade soils were classified according to AASHTO classification for each segment of Lane 6 North. Soil classification with respect to each segment is shown in Appendix E, Soil Type Map. A summary of soil type within each pavement section is shown in Table 5.

Table 5 - Summary of Soil Type per Pavement Segment

Segment Number

Lane 6 North Location

Subgrade AASHTO Soil Type

1 Milepost 0.0 (at SH17) to 4.5 (east of CR113) A-2-4 (0) 2 Milepost 4.5 to 9.2 (at canal) A-4 (0), A-4 (1), A-6 (1), A-6 (5), A-2-4 (0) 3 Milepost 9.2 to 12.0 A-2-4 (0), A-3 (0) 4 Milepost 12.0 to 12.6 A-3 (0) 5 Milepost 12.6 to 13.3 A-2-4 (0) 6 Milepost 13.3 to 16.1 (at SH150) A-2-4 (0), A-1-b (0)

6.2.2 Penetration Resistance

Penetration Tests were performed at selected intervals using an automatic hammer lift system and rope-cathead hammer lift system. The standard split spoon sampling method is the Standard Penetration Test (SPT) described by ASTM Method D-1586. Penetration Tests were performed using the modified California barrel sampler with a standard hammer weighing 140 pounds falling 30 inches per ASTM D3550. The modified California Barrel sampling method is similar to the SPT test with the difference being the sampler dimensions and the number of 6-inch intervals driven with the hammer. It is RockSol’s experience that blow counts obtained with the modified California sampler tend to be slightly greater than a standard split spoon sampler. Penetration resistance values (blow counts) were recorded for each sampling event. Blow counts, when properly evaluated, indicate the relative density or consistency of the soils.

Blow counts of coarse-grained soils ranged from 9 blows per foot to 50 blows for 4 inches. EB-4 was the only borehole with fine grained soils which ranged in blow counts from 29 to 34 blows per foot. Blow counts for each sample can be found on the Borehole Logs presented in Appendix B.

6.2.3 Classification

Fill Material Fill material was encountered in all boreholes to depths ranging from 2 feet to 6 feet below existing grades. Fill material generally consisted of medium dense to very dense, light brown to dark brown, moist, silty to clayey sand. Sandy clay fill material was encountered at Borehole EB-4. The fill soils were classified as A-2-4 (0), A-4 (0), A-4 (1), A-6 (1), A-6 (5), A-1-b (0), and A-3 (0) soils by AASHTO soil classification system.

Native Soils Native soils were encountered below the pavement and fill materials. The native soils encountered generally consisted of light brown slightly silty to clayey sand. Dark gray, wet sand was encountered from 7.5 to 9 feet below grade in Boreholes B-2, B-5, B-6, and B-8 through 10.

See Appendix B for the logs for the subgrade soil types encountered at each borehole location.

6.2.4 Chemical Properties

Cementitious material requirements for concrete in contact with site soils or groundwater are based on the percentage of water-soluble sulfate in either soil or groundwater that will be in contact with concrete constructed for this project. Mix design requirements for concrete exposed to water soluble sulfates in soils or water is shown in Table 6 - Requirements to Protect Against Damage to Concrete by Sulfate Attack from External Sources of Sulfate, and in the Standard Specifications for Road and Bridge Construction, dated 2019 (from the Colorado Department of Transportation (CDOT) Table 601-2).

Table 6 - Requirements to Protect Against Damage to Concrete by Sulfate Attack from

External Sources of Sulfate Severity of sulfate exposure

Water-soluble sulfate (SO4), in dry soil, percent Sulfate (SO4), in water, ppm Water Cementitious

Ratio, maximum Cementitious

Material Requirements

Class 0 0.00 to 0.10 0 to 150 0.45 Class 0 Class 1 0.11 to 0.20 151 to 1,500 0.45 Class 1 Class 2 0.21 to 2.0 1,500 to 10,000 0.45 Class 2 Class 3 2.01 or greater 10,001 or greater 0.40 Class 3

Soil from Borehole EB-4, EB-5, and WB-3 contain 0.13, 0.17, and 0.17 percent water-soluble sulfates, respectfully. Therefore, Class 1 cementitious materials are required for this project. All other boreholes tested below 0.10 percent water-soluble sulfates.

6.2.5 Corrosion Properties of On-site Soils

Water soluble chloride content, pH and electrical resistivity tests were performed on bulk samples obtained from the boreholes. The electrical resistivity analyses were performed in the RockSol laboratory using the soil box method (ASTM G-187). Sulfate, chloride, and pH tests were compared with the Guidelines for Selection of Corrosion Resistance Levels shown in Table 7 as presented in the CDOT Pipe Materials Selection Guide, dated April 30, 2015 to determine the minimum protection requirements for concrete pipes.

Table 7 - Guidelines for Selection of Corrosion Resistance Levels

SOIL WATER

CR Level Sulfate Chloride Sulfate Chloride

(SO4)

% max

(Cl) % max pH (SO4) ppm (max)

(Cl) ppm (max) pH

*CR 0 0.05 0.05 6.0-8.5 50 50 6.0-8.5

CR 1 0.10 0.10 6.0-8.5 150 150 6.0-8.5

CR 2 0.20 0.20 6.0-8.5 1,500 1,500 6.0-8.5

CR 3 0.50 0.50 6.0-8.5 5,000 5,000 6.0-8.5

CR 4 1.00 1.00 5.0-9.0 7,500 7,500 5.0-9.0

CR 5 2.00 2.00 5.0-9.0 10,000 10,000 5.0-9.0

CR 6 >2.00 >2.00 <5** or >9 >10,000 >10,000 <5** or >9

*No special corrosion protection recommended when values are within these limits.

**Concrete pipe used when the pH of either the soil or water is less than 5 shall be coated in accordance with subsection 706.07 of CDOT’s Standard Specifications for Road and Bridge

Construction.

Lab data and corrosion resistance levels are summarized in Table 8, below.

Table 8 - Corrosion Resistance Lab Testing Results

Borehole

ID

Sample Depth (Feet)

Water- Soluble

Chlorides (% max) pH

Resistivity (Ohm-cm)

@ Moisture Content (%)

Water- Soluble Sulfates (% max)

Corrosion Resistance

Level

EB-1 0.38 – 5 0.0102 9.4 23,000 @ 6.5 0.00 CR 6

EB-2 0.21 -- 5 0.0090 9.2 5,500 @ 14.2 0.00 CR 6

EB-3 0.35 – 5 0.0105 9.6 18,000 @ 8.0 0.00 CR 6

EB-4 0.5 – 5 0.0120 10.5 480 @ 21.1 0.13 CR 6

EB-5 0.46 -- 5 0.0135 10.8 710 @ 16.6 0.17 CR 6

EB-6 0.23 -- 5 0.0081 8.8 10,500 @15.55 0.00 CR 4

EB-7 0.54 – 5 0.0087 9.0 5,400 @ 17.84 0.00 CR 4

EB-8 0.47 – 5 0.0090 9.1 5,000 @ 16.89 0.00 CR 6

EB-9 0-42 – 5 0.0084 8.5 20,000 @ 5.4 0.00 CR 0

WB-1 0.29 – 5 0.0060 9.5 3,200 @ 14.1 0.00 CR 6

WB-2 0.43 – 5 0.0069 9.1 5,500 @ 15.18 0.00 CR 6

WB-3 0.33 – 5 0.0081 10.2 2,200 @ 11.21 0.17 CR 6

WB-4 0.54 – 5 0.0069 9.1 1,700 @ 21.27 0.03 CR 6

WB-5 0.59 – 5 0.0063 9.2 3,600 @ 6.7 0.00 CR 6

WB-6 0.29 – 5 0.0063 9.1 44,000 @ 6.7 0.00 CR 6

WB-7 0.42 – 5 0.0078 8.8 2,000 @ 18.46 0.00 CR 4

WB-8 0.5 -- 5 0.0066 8.7 10,200 @ 7.78 0.00 CR 4

Comparison of the test results of the sulfate, chloride, and pH testing performed with Table 1 - Guidelines for Selection of Corrosion Resistance Levels as presented in the CDOT Pipe Materials Selection Guide, dated April 30, 2015, suggests corrosion resistance (CR) levels of CR 0, CR 4, and CR 6 are present within the project limits. Of the three variables (water-soluble sulfate, water-soluble chloride, and pH) that are used in determining the CR level, the pH levels appear to be the predominant component affecting the CR level selection, with water-soluble chlorides also affecting the sample from EB-5, EB-6, and WB-3.

In addition, electrical resistivity analyses were performed in the RockSol laboratory using the soil box method (ASTM G-187). The results of the electrical resistivity tests were compared with the minimum pipe thickness for metal pipes based on the resistivity and pH of the adjacent soil shown in Table 9 as presented in the CDOT Pipe Materials Selection Guide, dated April 30, 2015. Based on test results, it is recommended that 0.052-inch (18 Gauge) Polymer Coated metal pipe be used when necessary.

Table 9 - Minimum Pipe Thickness for Metal Pipes Based on the Resistivity and pH of the

Adjacent Soil

SOIL SIDE MINIMUM REQUIRED GAUGE THICKNESS

FOR METAL PIPE MATERIAL

Resistivity, R (Ohm – cm) pH

≥1,500 5.0-9.0 0.052 in (18 Gauge) Aluminized Type 2

≥250 3.0-12.0 0.052 in (18 Gauge) Polymer Coated

Note: For these roadway segments, we have estimated low to moderate abrasive conditions which suggests Abrasion Level 2 or 3 should be used.

6.2.6 Swell / Consolidation

Swell/consolidation testing was performed on two subgrade samples collected using Modified California samplers. The sample from Borehole EB-1 at 5 feet below grade exhibited consolidation of 0.6 percent and the sample from Borehole EB-3 at 5 feet below grade exhibited consolidation of 1.2 percent when placed under an applied pressure of 500 psf.

6.2.7 Resistance “R” Values

To test the subgrade support characteristics for pavement design purposes, R-Value laboratory tests were performed on samples obtained from Boreholes WB-2, EB-4, B-3, and EB-7. A summary of R-Value test results is shown in Table 10.

Table 10 – Summary of R-Values Borehole Sample Depth

(feet) AASHTO Classification R-Value

WB-2 0.43 - 5 A-2-4 (0) 71

EB-4 0.5 - 5 A-6 (5) <5

B-3 0.625 – 4 A-4 (1) <5

EB-7 0.54 – 5 A-3 (0) 70

6.2.8 Proctor Values

Three standard proctor tests and two modified proctor tests were performed on the subgrade soil samples taken within 5 feet of pavement surface. The maximum dry density ranged from 109.8 to 139.5 pounds per cubic foot with an optimum moisture content ranging of from 6.0 to 15.8 percent. Test results can be found in Appendix D. A summary of the Proctor test results is presented in Table 11.

Table 11 – Proctor Test Results

Borehole Sample Depth

(ft)

AASHTO

Soil

Class

Maximum Dry

Density (pcf)

Optimum Moisture Content

Proctor S = Standard M = Modified

B-3 0.625-4 A-4 (1) 109.8 15.8 S B-5 0.46-4 A-2-4 (0) 124.6 9.7 M

EB-4 0.5-5 A-6 (5) 115.1 14.5 S

EB-7 0.54-5 A-3 (0) 117.9 10.9 S

EB-9 0.42-5 A-1-b (0) 139.5 6 M

7.0 PAVEMENT DESIGN RECOMMENDATIONS

The geotechnical investigation was performed in pavement areas for the purpose of pavement design. The subsurface conditions encountered in the borings may not be representative of conditions outside the roadway prism. The subsurface conditions at the site may not become evident until excavation is performed. If after performing excavation, conditions appear to be different from those described herein, this office should be advised so that we may reevaluate of the recommendations made.

Pavement designs for the proposed improvements for Lane 6 North, in Alamosa County, Colorado, as part of the Federal Lands Access Program were performed in accordance with methods outlined in Chapter 11 of the FLH Project Development and Design Manual (PDDM), 1993 AASHTO Guide for the Design of Pavement Structures (AGDPS), and the Pavement Mechanistic-Empirical Design (PMED) at defined in the 2021 CDOT Pavement Design Manual.

The recommendations of this report assume that grading, fill materials, aggregate base course, full depth recycling and pavement will be placed and constructed in accordance with the FHWA’s Standard Specifications for Construction of Roads and Bridges (FP-14) and CDOT’s Standard Specifications for Road and Bridge Construction (SSRBC). Compliance with these specifications is needed for the recommendations in this report to remain applicable. The 1993 AGDPS design inputs and calculations are presented in Appendix F while the PMED design outputs are presented in Appendix G.

7.1 Pavement History

The County staff reported first surface pavement was placed on Lane 6 North in 1983. The existing pavement has received at least one chip seal and has been crack sealed throughout its life. A minor overlay has been placed at locations noted below and County maintenance staff have placed numerous full-depth patches.

7.2 Design Traffic Volume

The traffic study consisted of average daily traffic (ADT) and assumptions for vehicle distribution provided to us by Jacobs in a memorandum dated February 5, 2021 which provided 2021 ADT values of 650 vehicle per day (vpd) for Lane 6 North. The vehicle distribution was estimated to be 77% passenger cars, 9% pickup trucks or vans, 3% single unit trucks and busses, and 11% combination tractor trailer trucks. In our analysis, we assumed that project completion would occur in 2022. From Section 11.2.1.2 of the PDDM, we used the recommended directional distribution of 60% for a two-lane facility. We estimated an 18-kip equivalent single axle load (ESAL) of approximately 805,000 for this project based on an average truck factor shown in Exhibit 11.2 of the PDDM, a 25-year design life as indicated for a rehabilitation (3R) project, and a 2% annual growth rate. Our estimated ESALs calculations are provided in Appendix F. The PMED method does not include light weight vehicles such as cars and pickup trucks therefore, the percentage of trucks used in PMED were prorated from the total ADT distribution to equal 100 percent as shown in Table 12.

Table 12 - Vehicle Class Distribution Class of Vehicle Type of Vehicle ADT

PMED

1 Motorcycles 0.37 0.00 2 Passenger Cars 76.92 0.00 3 Pickup trucks, Vans, and Campers 9.30 0.00 4 Buses 0.15 1.12

5 Two-axle Single-Unit Trucks, Recreational Vehicles, and Motor Homes 1.27 9.47

6 Three-Axle Single-Unit Trucks, Recreational Vehicles, and Motor Homes 0.48 3.58

7 Four or More Axle Single-Unit Trucks 0.01 0.07

8 Four or Fewer Axle Single-Trailer Trucks 1.76 13.12

9 Five-Axle Single-Trailer Trucks 9.54 71.14

10 Six or More Axle Single-Trailer Trucks 0.18 1.34

11 Five or fewer Axle Multi-Trailer Trucks 0.00 0.02

12 Six-Axle Multi-Trailer Trucks 0.01 0.07

13 Seven or More Axle Multi-Trailer Trucks 0.01 0.07

7.3 Structural Section

As reported in RockSol’s Preliminary Pavement Recommendations memo dated December 31, 2020, results of 17 borings show that the existing pavement thickness ranges from 2.5 to 6.5 inches while the existing pavement in patched locations (Boreholes B-1 through B-10) ranged from 4.0 to

7.5 inches. Base course was encountered beneath the pavement in most of the borings with a thickness ranging from 0 to 7.5 inches. Base course material was not encountered beneath the patched pavement. Natural subgrade materials generally consist of sand with silt to a clay with sand.

The R-Values obtained from on-site soils were converted to Resilient Modulus (Mr) using equation

4.1 found in CDOT’s 2021 PDM. Pavement Design Variables, set in accordance with Section 11.2 of the FLH Project Development and Design Manual (PDDM), are as follows:

• Serviceability: Initial = 4.2 (flexible pavement); Terminal = 2.5 (roadways with ADT between 500 and 5,000)

• Design Period: 25 years (Reconstruction)

• Design ESALs (W18) = 805,000

• R = 70; Mr = 11,075 psi (Segments 1, 4, 5, and 6) and R = 5; Mr = 5,355 psi (Segments

2 and 3)

• Minimum Reliability Level (R): 75 (roadways with ADT < 5,000)

• Overall Standard Deviation (So): 0.49

The resulting minimum required Structural Numbers (SN), given these input parameters, are 3.473 for R = 5 and 2.627 for R = 70. Structural Coefficients for each surfacing material were assigned based on values provided in the FLH PDDM Exhibit 11.2-C, Layer Types and Coefficients, and gives a range of 0.40 to 0.44 for HACP Item(s) 401 and 402. A coefficient of 0.44 was assigned to all new HACP. Given the consistent high severity full-depth pavement cracking, damaged and irregular roadway pavement edges throughout, extreme pavement age and poor overall pavement condition throughout the length of the project, Full-Depth Reclamation (FDR) is being considered for reconstruction of the entire existing roadway pavement. The FDR process involves pulverizing and mixing the existing asphalt with the underlying material to create a uniformly blended, homogeneous material that will be used in the proposed pavement section as an improved base course layer to provide more uniform support throughout the length of the project. The benefit of the FDR process is that it allows the existing material to be recycled in place, eliminates the expense to export the old, damaged pavement material offsite, and produces a more uniform structural layer that contributes to optimized thickness and performance in the final HACP surface. Exhibit 11.2-C gives a range of

0.10 to 012 for pulverized FDR. An average layer coefficient of 0.11 was used in our analysis for FDR locations with subgrade soils with an R-Value above 70. For segments with low R-Value subgrade, the addition of 4% cement should be blended with the FDR material. Exhibit 11.2-C gives a range of 0.15 to 022 for FDR with cement. A layer coefficient of 0.22 was used in our analysis. In our opinion, a blended material of pulverized asphalt, existing native soils, and 4% cement will likely exceed this requirement. The resulting designs, presented in Appendix F, achieve the required SN’s.

Since CDOT recommends the use of AASHTO Mechanistic-Empirical (M-E) design procedures and the PDDM references DARWin-ME as source information in developing Chapter 11, we used AASHTOWare’s Pavement M-E Design (previously known as DARWin-ME) software version

2.3.1 as outlined in CDOT’s 2021 PDM.

Based on the Guide to Full-Depth Reclamation (FDR) with Cement published by the National Concrete Pavement Technology Center in March 2017 (Reprinted January 2019), we are estimating the unconfined compressive strength to be at least 200 psi when blending 4% cement with the FDR material and R-Value 5 subgrade soil. Table 2-1 from the Guide to Full-Depth Reclamation (FDR) with Cement shows that a resilient modulus of 516,000 psi could be expected with a compressive strength of 200 psi. The resulting designs, presented in Appendix G, do not exceed the distress thresholds for principal arterial roadways as shown in Table 2.4 of CDOT’s 2012 PDM.

For information only and to help estimate project bid item quantity for cement, RockSol conducted laboratory testing in general conformance to FP-14 Section 305 on prepared cement-stabilized FDR samples. Project production cement content will be based on the FDR contractor’s mixture design. See Appendix H for a summary of the test results. Given the anticipated variability in moisture content and production control at this arid project site, the varied soil types, and the changes in FDR-blend composition across the treated project segment, 4% cement is expected to produce the designed FDR structural layer strength and to promote uniform support to the final HACP pavement.

Multiple alternatives were provided in the Preliminary Pavement Recommendations memo. This report presents the alternates selected for final design. The preliminary memo is provided in Appendix I, for reference.

7.3.1 Milepost 0.0 to 4.0 and Milepost 8.0 to 16.0

For these locations, subgrade soils were found to be sandy soils with a high R-Value. Full depth reclamation (FDR), in accordance with FP-14 Section 304, to a typical depth of 8 inches, followed by a structural HACP overlay, is the recommended rehabilitation method. In order to incorporate a supporting base for the new pavement safety edge, prior to the FDR operation the top 8 inches of the existing shoulder material should be bladed out or removed for a minimum width of at least one foot beyond the existing pavement edge and the underlying soils should be reconditioned and compacted. The FDR will process the existing pavement, existing base course, and a portion of the subgrade soil to provide a total thickness of 8 inches in one pass. The processed FDR material should be reshaped to extend one foot beyond the existing outside edge of pavement. After reshaping, moisture-conditioning, and compacting, a minimum of 7 inches of processed FDR will exist across the full finished width (approximately 13 feet in each direction). The finished and compacted FDR layer will be surfaced with 3 inches of HACP, with a safety edge, placed in two 1.5-inch lifts.

7.3.2 Milepost 4.0 to 8.0

For this location, subgrade soils were found to be variable clay soils with a low R-Value resulting in non-uniform subgrade support and numerous localized pavement structural failures. Due to the historic pavement failures, the thicker (5.8-inch average) existing pavement, and the need to develop a more substantial and uniform supporting base layer over the variable underlying soils in this area, full depth reclamation (FDR) stabilized with cement, in accordance with FP-14 Section 305, to a total depth of 12 inches, followed by a structural HACP overlay is the recommended rehabilitation method.

In order to incorporate a supporting base for the new safety edge, prior to the FDR operation the top 12 inches of the existing shoulder material should be bladed out or removed for a minimum width of at least one foot beyond existing pavement edge and the underlying soils should be reconditioned and compacted. The FDR will process the existing pavement, existing base course, and a portion of the existing subgrade to total thickness of 12 inches in the first pass. The processed FDR material should be reshaped to extend one foot beyond the existing edge of pavement. After reshaping, approximately 11-inch-thick processed FDR material will exist across the entire finished pavement width (approximately 13 feet in each direction). The second FDR pass will moisture-condition and blend in the estimated 4% cement by weight into the 11-inch-thick finished processed material. The compacted FDR layer with cement will be surfaced with a 3-inch overlay of HACP with a safety edge placed in two 1.5- inch lifts. For estimating purposes, 4% cement should be used. Actual cement content production target for construction will be based on the FDR contractor’s cement-stabilized FDR mixture design, as approved prior to FDR work in accordance with FP-14 Section 305.

Significant deep patching of recurring failed pavement has been completed in this area generally as described by the Alamosa County Road and Bridge Director. Depths of subgrade removal and replacement were confirmed during borings to be approximately 4 feet and typical new asphalt was placed at typical depth of 6 inches. The replacement embankment material placed in these patch areas was described by the County as “pit run” material, but it does not appear to be significantly processed, coarse or crushed aggregate fill materials. All of the visible existing patched areas were performing well at the time of the pavement condition evaluation. Several small areas of pavement adjacent to existing completed patches were cracked and deformed, showing signs of structural failure. These isolated distressed pavement surface areas are recommended for repair during construction. Each area shall be marked for removal to a minimum of 2-feet beyond the extents of the visible distress in the surface pavement, subexcavated to a minimum depth of 4 feet, backfilled with select borrow, and patched with minimum 4” HACP. All subexcavation, select borrow, and HACP patching work shall be completed prior to the cement-stabilized FDR operations. Total pavement repair locations and plan quantities should be as necessary to repair all locations with evident distress at the time of construction. Subexcavation and select borrow work items shall be completed in accordance with FP-14 Section 204.

7.4 Hot Asphalt Concrete Pavement Mix and Binder

We recommend a ½ inch (12.5 mm) Nominal Maximum Size Aggregate with a 75-design gyratory asphalt concrete mix design, conforming to FP-14 Table 401-1 for this project with a Design ESAL between 0.3 and 3.0 million. Aggregates should meet the requirements presented in subsection

703.07 and Table 703-4 of FP-14.

The preferred asphalt binder for the top 1.5-inch lift is PG 64-28 and a PG 64-22 for the 1.5-inch lift below the top lift, as recommended by CDOT’s Pavement Design Manual for the project conditions.

8.0 GEOTECHNICAL RECOMMENDATIONS

8.1 Earthwork Design

8.1.1 General Grading

Prior to construction of new pavements on subgrade soils, the underlying subgrade should be properly prepared by removal of all organic matter (topsoil), debris, loose material, and any deleterious material identified by the Project Engineer followed by scarification, moisture conditioning and recompacted. Unless otherwise specified, the minimum depth of scarification, moisture conditioning and re-compaction in all cases shall be 6 inches. Cobbles greater than 3 inches in diameter, if encountered, should be removed from the scarification zone. Subexcavated areas within existing embankments comprised primarily of clayey soils that are backfilled for localized stabilization and patching with permeable granular select backfill should be extended to the outside roadway embankment side slope to “daylight” the new permeable backfill to allow the draining of water, and to prevent the concentration of water within the new backfill beneath the finished pavement structure.

For all new pavement areas, proof rolling with pneumatic tire equipment shall be performed using a minimum axle load of 18 kips per axle after specified…