CO_FLAP_CHA_306(1)_Pavements_Report_Signed.pdf

COTTONWOOD PASS EAST SIDE

CHAFFEE COUNTY, COLORADO

CO FLAP CHA 306(1)

PAVEMENT AND MATERIALS REPORT

NOVEMBER 2017

Report prepared by:

U.S. Department of Transportation Federal Highway Administration

Central Federal Lands Highway Division Lakewood, Colorado http://www.google.com/imgres?sa=X&biw=1280&bih=819&tbm=isch&tbnid=gtpyJEKxSQX6SM:&imgrefurl=http://portal.hud.gov/hudportal/HUD?src=/press/press_releases_media_advisories/2010/HUDNo.10-242&docid=0hzyuk4oobnONM&imgurl=http://portal.hud.gov/hudportal/images/hudimg?id=dot_logo_41193.jpg&w=520&h=528&ei=uGw7Uoy6Ksjk4AOC_IDQBw&zoom=1&iact=hc&vpx=567&vpy=131&dur=635&hovh=226&hovw=223&tx=151&ty=150&page=1&tbnh=154&tbnw=162&start=0&ndsp=30&ved=1t:429,r:26,s:0,i:171

CO FLAP CHA 306(1) Cottonwood Pass East Side ii

Written by:

Rick Marquez, Quality Assurance Specialist, Rocksol Consulting Group

Reviewed by:

Robert Norick, Pavements & Materials Engineer, FHWA

Approved for distribution by:

Mike Voth, Senior Pavements & Materials Engineer, FHWA Date

Electronic Distribution:

Construction Project Development Project Management Technical Services

H. Rick Marquez 11-7-17 iii

TABLE OF CONTENTS

I. INTRODUCTION

II. CLIMATE

III. PAVEMENT ASSESSMENT

IV. EXISTING PAVEMENT, BASE, AND SOILS

V. PAVEMENT DESIGN INPUTS

VI. PAVEMENT RECOMMENDATIONS & DISCUSSION

VII. MATERIALS RECOMMENDATIONS AND SCRs

APPENDICES

A – Vicinity Map, Site Map, & Test Pit Log B – Pavement Assessment Photos C – Excerpts from 1982 Materials Investigation D – Excerpts from 1987 Materials Investigation E – Excerpts from 1996 Materials Report F – Pavement Design Calculations G – LTPPBind and Climate Data

I. INTRODUCTION

This report is written to document the existing road conditions and provide pavement recommendations for the planned CO FLAP CHA 306(1) Cottonwood Pass East Side project, Chaffee County, Colorado. The project begins at the top of Cottonwood Pass and proceeds east 18.5 miles through the Gunnison National Forest to County Road 321 (Rodeo Road) in the Town of Buena Vista. The upper 0.5 mile section is proposed to be widened and shifted into the cut slope (left) to move away from embankment distress (right), to eliminate the need for guardrail, and to provide a rockfall storage area (left).

Rehabilitation is proposed for the remaining 18 miles, including pulverization, subgrade stabilization, asphalt overlay, rock scaling, guardrail replacement, select culvert replacement, and installation of signing and striping. This work may also include the installation of buried conduit for a future Century Link cable system, Option Z. The existing asphalt paved road is 22 to 26 feet wide with two 11 foot drive lanes. The drive lane width will remain 11 foot with the proposed rehabilitation. Construction options to build 2 foot wide shoulders on both sides of the road or 6 foot wide bike lanes on both sides of the road between County Roads 342 and 321, have been developed, Options X and Y, respectively. Vicinity and Site maps for the project are provided in Appendix A.

II. CLIMATE

Climate data was obtained from RAWS USA Climate Archive for the Taylor Park, CO weather station. The data is summarized in Table 1 below and provided in Appendix G.

The average precipitation for this area is approximately 16.81 inches. The project is located at an elevation that receives both snow and rain, dependent upon the time of year.

The project ranges in elevation from ≈8,110 feet to ≈12,120 feet.

Table 1. Weather Data

Month Average

HIGH

Record

HIGH

Average

LOW

Record

LOW

Average

PRECIP.

January 26.8 54 -10.5 -56 1.36”

February 31.9 51 -8.7 -60 1.29”

March 38.0 61 0.1 -42 1.44”

April 45.9 67 14.6 -29 1.38”

May 56.3 82 26.8 -5 1.32”

June 67.3 85 34.2 15 0.97”

July 71.8 86 40.9 20 1.84”

August 69.4 84 39.8 17 1.83”

September 63.5 79 32.3 4 1.40”

October 53.3 75 23.7 -5 1.31” November 38.5 65 10.2 -30 1.26” December 27.9 57 -5.5 -53 1.40”

Temperatures are in °F and precipitations are in inches.

III. PAVEMENT ASSESSMENT

A comprehensive pavement and subgrade investigation was not requested for the project.

The pavement assessment for the project included the following:

• Pre-scoping Review , September 1-2, 2016

• Scoping Site Visit, September 26-28, 2016

• Subgrade Investigation, October 5, 2016

• Pavement Core Drilling, July 12, 2017

The October 2016 subgrade investigation consisted of backhoe test pits along the road shoulder for some of the areas with severe pavement distress with the purpose of determining the anticipated depth of subexcavation for adequate roadway stabilization (See Test Pit Log in Appendix A). The July 2017 core drilling was performed for verification of the existing pavement thickness and to verify the feasibility of an 8-inch deep full depth reclamation (i.e. verify thickness of existing crushed aggregate base and pavement).

IV. EXISTING PAVEMENT, BASE, AND SOILS

The existing roadway was found to be in poor condition. The existing asphalt pavement exhibits transverse, longitudinal, block, edge, and alligator cracking throughout its length.

The pavement thickness ranges between 2 and 2.5 inches. The pavement was installed with two CFLHD projects in 1987 and 1991; 25 to 30 years old. The upper 7.5 miles of the route has never received a pavement preservation treatment (e.g. chip seal) and has numerous areas with subgrade failures. The lower 11 miles received a chip seal in 2005- 2006. The age of the existing pavement is beyond its design life with extensive and widespread pavement distresses. The pavement life cannot be extended with pavement preservation and rehabilitation methods (e.g. chip seals and overlays). Similar to the pavement, the ditches along the route have received minimal maintenance, if any at all.

The lack of adequate ditch maintenance has contributed in some areas to poor drainage and possibly contributed to some of the pavement distresses. The following Table 2 summarizes the previous CFLHD construction sequencing of the route over the 6-year period between 1985 and 1991, as wells as, the depth of the original aggregate base and asphalt pavement. The stationing shown in Table 2 is the current stationing (original stationing plus 1000+00). As part of the pavement assessment, the pavement was core drilled in July 2017 to verify the pavement thickness and to verify the feasibility of an 8” deep full depth reclamation. The data from this core drilling operation is presented in the subsequent Table 3 (both original and current stationing provided). Based upon the previous projects, the subgrade soils along the route are generally silty sands with gravel.

Table 2. Original Construction Dates and Pavement Sections

PROJECT YEAR STATION-TATION LENGTH

(MI)

AGG.

BASE(IN.)

HACP (IN.)

59-3(1) 1985-1986 3077+16 - 3435+10 6.78 12 0 59-3(2) 1986-1987 3435+00 – 3737+00 5.72 6 2 59-3(3) 1990-1991 3077+16 – 3471+76

3740+00 – 3845+00 3845+00 - 4056+72

7.47 1.99 4.01

8-12

2.5 2(on milled surface)

Table 3. Verification of Existing Pavement Sections (July 2017 Coring Data)

V. PAVEMENT DESIGN INPUTS

The pavement design for Cottonwood Pass East Side utilizes design criteria established in the Federal Lands Highway (FLH) Project Development Design Manual (PDDM). The criteria shown in Table 4 were selected based on the project’s scope and traffic levels.

Table 4. Design Criteria for Cottonwood Pass East Side Design Performance Period (3R) 20 years Initial Serviceability 4.2 Terminal Serviceability 2.5 Design Reliability Level 75% Overall Standard Deviation 0.49 Directional Distribution 60%

Traffic

Current traffic data is not available for Cottonwood Pass. The upper section of the road (7.5 miles) is seasonal, typically opening by Memorial Day (late May) and closing by late October or early November. The lower section of the road out of Buena Vista (11 miles) is open year round. Based upon September 2015 traffic counts, Chaffee County determined the road’s two-way seasonal average daily traffic (ADT) to be 1,500 vehicles per day. The off-season traffic is assumed to be half of the seasonal traffic or 750 vehicles per day. Based upon 5 months of seasonal traffic (1,500 ADT) and 7 months of off-season traffic (750 ADT), the annual average daily traffic (AADT) is 1,000 vehicles per day. Cottonwood Pass is used primarily for recreational purposes with the majority of vehicles being passenger vehicles, pickups, SUVs, and recreational vehicles. There are occasional delivery trucks or freight trucks that utilize the route. Accurate traffic load estimates expressed as 18-kip equivalent single axle loads (ESAL) are critical for the

Original-station

Current Station

0riginal-

AC-IN

0riginal-

CAB-IN

MP

Actual

MP

Lane

Measured

AC-IN

Measured Base-IN

Remarks

207716 307716 2.5 12 0 1 212996 312996 2.5 12 1 0.51 R 2.00 6+

218276 318276 2.5 12 2 2 223556 323556 2.5 12 3 2.53 L 2.00 6+

228836 328836 2.5 12 4 3 234116 334116 2.5 12 5 4.51 R 2.00 6+

239396 339396 2.5 12 6 4 244676 344676 2 6 7 6.55 L 2.25 6+ 5 249956 349956 2 6 8 7.51 R 1.75 9+

255236 355236 2 6 9 6 260516 360516 2 6 10 9.47 L 1.75 6+

265796 365796 2 6 11 7 271076 371076 2 6 12 11.52 R 4.00 6+ 8 276356 376356 2 6 13 12.41 R 2.50 6+ 9 281636 381636 2 6 14 13.42 L 1.75 6+ 10 286916 386916 2 6 15 14.50 R 2.25 6+ Pulverized Base 11 292196 392196 2 6 16 15.54 L 2.00 6+ Pulverized Base 12 297476 397476 2 6 17 16.54 R 2.00 6+ Pulverized Base 13 302756 402756 2 6 18 17.65 L 2.00 6+ Pulverized Base

405452 2 6 18.511 18.441 Pulverized Base pavement design. Load estimates are based on the AADT and vehicle classifications with a 20-year, 2% growth factor of 24.3. Standard load equivalency truck factors are used to convert the various vehicle axle loads to an 18-kip ESAL. The vehicle classifications and truck factors are in accordance with PDDM Exhibit 11.2-A. Based upon field observations, the following vehicle classifications and distributions are assumed for the project’s pavement design: 88% Class 2-3 cars/pickups (0.004 truck factor), 10% Class 5 motor homes and delivery trucks (0.5 truck factor), and 2% Class 9 tractor trailer trucks (2.0 truck factor). Based on the design criteria and assumptions shown above and the 1993 AASHTO pavement design procedure, the project’s 20-year-18-kip equivalent single axle loads (ESAL) are calculated to be 497,632 (see Appendix F).

Subgrade Soil Resilient Modulus

The previous Cottonwood Pass subgrade investigations in 1982, 1987, and 1996 collected subgrade samples for R-Value (AASHTO T190) testing (excerpts provided in appendices). The subgrade soils along the route are generally silty sands with gravel. The R-Value (resistance value) is a measure of a material’s resistance to deformation under load on a scale of 0 (water) to 100 (steel). The subgrade Resilient Modulus (modulus of elasticity) is calculated from the R-Value using the following correlation equation:

Resilient Modulus, MR (psi) = 10[ ( S

+ 18.72 ) / 6.24 ] where the S1 factor = [(R-Value – 5) / 11.29] + 3

The average R-Values from the previous investigations are as follows:

• 1982 Investigation: Average R-Value = 71 for 7 Samples

• 1987 Investigation: Average R-Value = 60 for 14 Samples

• 1996 Investigation: Average R-Value = 55 for 18 Samples

The average R-Value for the previous three subgrade investigations (39 samples), as well as, the design R-Value from the 1982 pavement design is 60. This R-Value is also utilized for the current Cottonwood Pass East Side pavement design with a corresponding design Resilient Modulus of 18,000 psi.

Structural Layer Coefficients

Standard CFLHD structural layer coefficients were selected for asphalt pavement, 0.44, and crushed aggregate base (CAB)/full depth reclamation (FDR), 0.12, in accordance with Exhibit 11.2-C of the PDDM. A drainage coefficient of 1.0 was used for all layers.

Structural Number Calculations

The Pavement Interactive App for the 1993 AASHTO pavement design procedure is used to determine the required pavement structural number (SN) for the project. Based upon the ESALs, the subgrade Resilient Modulus, and the aforementioned design criteria, the following required pavement design structural number is calculated.

Cottonwood Pass East Side SN = 2.04 inches

VI. PAVEMENT RECOMMENDATIONS & DISCUSSION

Pavement Structural Section

In accordance with the 1993 AASHTO pavement design procedure and the required pavement structural number, the following pavement structural sections are proposed:

3 inches Asphalt Pavement (SN = 3” x 0.44 = 1.32”) 8 inches FDR - Pulverize (SN = 8” x 0.12 = 0.96”)

TOTAL SN = 2.28 inches

3 inches Asphalt Pavement (SN = 3” x 0.44 = 1.32”) 6 inches CAB/FDR Material (SN = 6” x 0.12 = 0.72”)

TOTAL SN = 2.04 inches

Pulverization should be from edge of pavement to edge of pavement. No existing pavement should remain after the road is pulverized. The hot mix asphalt (HACP) shall be in accordance with FP-14 Section 401. The full depth reclamation shall be in accordance with FP-14 Section 304.

Existing Pavement Fabric/Geotextile

Between approximate Stations 3468+00 and 3485+00, fabric/geotextile was previously installed beneath the aggregate base (approximately 8” below the existing pavement surface). Prior to proceeding with the full depth reclamation in this area, the Contractor shall “pot hole” to determine the exact limits of the fabric and shall develop a procedure/process to protect the existing fabric during the pulverizing operation.

Drainage

The ditches along the route have received minimal maintenance, if any at all. The lack of adequate ditch maintenance has contributed in some areas to poor drainage and possibly contributed to some of the pavement distresses. During the pavement assessment, water seepage and wet subgrade material was observed. There is some potential for water under the road in numerous areas. Ditch maintenance and underdrains are needed to prevent water from saturating the roadbed.

Subexcavation

The upper 7.5 miles of the route have numerous areas of subgrade failure that will require subexcavation to stabilize the failures. The subgrade failures were identified based upon the existing pavement distresses and subsequent backhoe test pits. It appears that the majority of these subgrade issues are the result of the failure to remove organic topsoil prior to the original embankment construction. The backhoe test pits identified dark organic topsoil at depths of 1 to 3 feet. Table 5 below shows estimated quantities for twelve areas of subgrade failure requiring subexcavation and stabilization. Other areas may be exposed during construction and shall be addressed per the subexcavation recommendations noted in this report. The stations indicated are to the approximate center of the distressed areas. The subexcavation shall consist of the following:

1. Prior to subexcavation, perform “pot holing” as directed by the CO to determine the final depths, lengths, and widths; paid for with equipment time.

2. Excavate subexcavation areas to required depths as measured from the bottom of the existing structural section (aggregate base).

3. Upon completion of excavation, place geotextile (fabric) over the area.

4. Backfill subexcavation areas to within 8” of the proposed bottom of pavement with suitable excess material generated from roadway excavation activities meeting AASHTO A-1. A-2, or A-3 soil classifications. Any additional material necessary shall be unclassified borrow material.

5. Place 8” of FDR material.

Table 5. Subexcavation Locations and Quantities

SITE STATION LENGTH

(FT)

WIDTH

(FT)

FABRIC

AREA (SY)

DEPTH

(FT)

SUBEX.

VOLUME

(CY)

1 3127 225 30 750 2.33 750

2 3148 275 30 917 2.23 917

3 3180 360 30 1200 2.33 1200

4 3195 450 30 1500 2.33 1500

5 3217 530 30 1767 2.33 1767

6 3260 275 30 917 2.33 917

7 3319 525 30 1750 2.33 1750

8 3324 224 30 747 2.33 747

9 3336 200 30 667 2.33 667

10 3347 150 30 500 2.33 500

11 3470 450 30 1500 2.33 1500

12 3481 275 30 917 2.33 917

TOTALS 13130 13130

Note: Station 3468 to 3485+00, 1700 LF of Geotextile, Contractor to Pot Hole to Determine Exact Locations.

VII. MATERIALS RECOMMENDATIONS AND SCRs

Selection of Asphalt Binder

The LTPPBind software was utilized for the selection of the asphalt binder for the project (See Appendix G). A PG 58-34 binder is recommended for the project’s asphalt pavement. This binder grade is used by the Colorado Department of Transportation (CDOT) in the cold regions throughout the state.

Pavement Roughness

It is recommended that pavement roughness be evaluated as Type III-B in accordance with FP-14 Section 401.16(d) and Table 401-5. Use of a material transfer vehicle (MTV) is required.

Prime and Tack Coats, Fog Seal and Blotter

For this project, a Prime Coat and Blotter applied to the base prior to asphalt placement, a Tack Coat applied between asphalt lifts, and a Fog Seal applied to the final pavement surface are recommended.

SCRs and Construction Concerns

CFLHD standard SCRs related to pavements and materials are expected to be used. Any additional SCRs may be developed as needed.

Bid Items

Suggested FP-14 pay items for the proposed structural section are shown in Table 6.

Table 6: Recommended Pay Items Item

Number Item Description Unit Remarks.

20402-0000 Subexcavation CUYD 30201-2000 Roadway Aggregate, Method 2 CUYD 30303-1000 Ditch Reconditioning MILE 30401-5500 Full Depth Reclamation, Method 2, 8-Inch Depth MILE

40101-5600 Asphalt Concrete Pavement, Gyratory Mix, 1/2- Inch or 3/4-Inch Nominal Maximum Size Aggregate, 0.3 To <3 Million ESAL

TON

40105-3000 Antistrip Additive, Type 3 TON 40601-0000 Fog Seal TON 41102-1000 Prime Coat, Method 1 SQYD 41105-0000 Blotter TON 41201-0000 Tack Coat TON

APPENDICES

A – Vicinity Map, Site Map, & Test Pit Log

B – Pavement Assessment Photos

C – Excerpts from 1982 Materials Investigation

D – Excerpts from 1987 Materials Investigation

E – Excerpts from 1996 Materials Report

F – Pavement Design Calculations

G – LTPPBind and Climate Data

CO FLAP 306(1) Cottonwood Pass East Side

APPENDIX A – Vicinity Map, Site Map & Test Pit Log

Cottonwood Pass East Side - Project Description & Vicinity Map

The project begins at the top of Cottonwood Pass and proceeds east 18.5 miles to County Road 321 (Rodeo Road) in the Town of Buena Vista. The upper 0.5 mile section is proposed to be widened and shifted into the cut slope (left) to move away from embankment distress (right), to eliminate the need for guardrail, and to provide a rockfall storage area (left).

Rehabilitation is proposed for the remaining 18 miles, including pulverization, subgrade stabilization, asphalt overlay, rock scaling, guardrail replacement, select culvert replacement, and installation of signing and striping. This work may also include the installation of buried conduit for a future Century Link cable system, Option Z. Construction options to build 2 foot wide shoulders on both sides of the road or 6 foot wide bike lanes on both sides of the road between County Roads 342 to 321, have been developed, Options X and Y, respectively.

Note that numerous manholes will need to be adjusted with the bike lane Option Y.

Personel Present: J. Arthurs, R. Marquez

Test Pit Number

Sta. Si de Repair

Section De pt h

Description Other observations

0-1" Topsoil

1"-6' GRAVEL with silt and sand (GP-GM) - light gray to brown to orange, moist, fine to coarse grained, cobbles up to 8" diameter, sub-rounded to sub-angular, low plasticity, iron stained at 3'

0-2" Topsoil

2" - 3' GRAVEL with silt and sand (GP-GM) - brown, moist, fine to coarse grained, cobbles up to 12" diameter, subrounded to subangular, low plasticity. Refusal/boulder at 3'.

0-3' (FILL) GRAVEL with silt and sand (GP-GM) - light brown, moist, fine to coarse grained, cobbles up to 4" diameter, rounded to sub-angular, low plasticity.

3'-3.4' (Topsoil) silty SAND (SM) - black, moist, fine to course grained with trace of gravel, low plasticity, woody debris, branches, roots.

3.4'-7' GRAVEL with silt and sand (GP-GM) - brown, moist, fine to coarse grained, cobbles up to 8" diameter, subrounded to subangular, low plasticity.

0-3' (FILL) GRAVEL with silt and sand (GP-GM) - brown, moist, fine to coarse grained, cobbles up to 4" diameter, rounded to sub-angular, low plasticity.

3'-3.3' (Topsoil) silty SAND - black, moist, fine to course grained with trace of gravel, low plasticity, woody debris, branches, roots.

3.3'-5.5' GRAVEL with silt and sand (GP-GM) - brown, moist to wet, fine to coarse grained, cobbles up to 8" diameter, subrounded to subangular, low plasticity. Water at 5.5'.

0-2' (FILL) GRAVEL with silt and sand (GP-GM) - brown, moist, fine to coarse grained, cobbles up to 4" diameter, rounded to sub-angular, low plasticity.

2'-2.3' (Topsoil) silty SAND (SM) - black, moist, fine to course grained with trace of gravel, low plasticity, woody debris, branches, roots.

2.3'-5.5' GRAVEL with silt and sand (GP-GM) - brown, moist to wet, fine to coarse grained, cobbles up to 8" diameter, subrounded to subangular, low plasticity. Water at 5.5'.

0-3' (FILL) GRAVEL with silt and sand (GP-GM) - brown, moist, fine to coarse grained, cobbles up to 4" diameter, rounded to sub-angular, low plasticity.

3'-3.2' (Topsoil) silty SAND (SM) - black, moist, fine to course grained with trace of gravel, low plasticity, woody debris, branches, roots.

3.2'-5' GRAVEL with clay and sand (GP-GC) - brown, moist to very moist, fine to coarse grained, cobbles up to 8" diameter, subrounded to subangular, low to medium plasticity.

7 3215+00 R 5 0-5' (FILL) GRAVEL with clay and sand (GP-GC) - brown, moist to very moist, fine to coarse grained, cobbles up to 10" diameter, medium plasticity. Very moist to wet below 3'.

Underdrain on left side of road.

8 3259+50 L 6 0-2' (FILL) GRAVEL with clay and sand (GP-GC) - brown, moist to very moist, fine to coarse grained, cobbles up to 10" diameter, low plasticity. Refusal at 2'.

9 3260+00 R 6 0-3' (FILL) GRAVEL with clay and sand (GP-GC) - brown, moist to very moist, fine to coarse grained, cobbles up to 10" diameter, low plasticity. Refusal at 3'.

0-1.5' SAND with clay (SP-SC) - light brown, moist, fine to coarse grained, trace of fine gravel, medium plastic, roots.

1.5'-4.5' GRAVEL with clay and sand (GP-GC) - brown, moist, fine to coarse grained, boulders up to 18" diameter, subrounded, low plasticity.

0-0.75' (FILL) Base Course, light brown, very moist

0.75'-2' poorly-graded GRAVEL with sand (GP), light brown, very moist, fine to course grained with cobbles, rounded to sub-rounded, non-plastic.

0-3' (FILL) GRAVEL with clay and sand (GP-GC) - light brown, moist, fine to coarse grained, cobbles up to 4" diameter, low plasticity.

3'-3.25' (Topsoil) silty sand (SM) - black, moist, fine to course grained with trace of gravel, low plasticity, woody debris, branches, roots.

3.25'-4' GRAVEL with silt and sand (GP-GM) - brown, moist, fine to coarse grained with cobbles and boulders, low plasticity.

13 3336+00 R 9 0-2' (FILL) GRAVEL with silt and sand (GP-GM) - brown, moist, fine to medium grained with cobbles and boulders, low plasticity.

0-0.5' silty SAND with gravel (SM) - light brown, moist, fine to coarse grained, low plasticity.

0.5'-2.5' (FILL) silty GRAVEL with sand (GM) - light brown, moist, fine to coarse grained with cobbles and boulders up to 24" diameter, low plasticity.

2.5'-4.5' GRAVEL with silt and sand (GP-GM) - brown, moist to wet, fine to coarse grained, cobbles up to 24" diameter, rounded to subrounded, low plasticity. Water at 4'.

Water flowing from SW to

NE.

0-3" Asphalt 3"-9" Base

9"-1.5' GRAVEL with silt and sand (GP-GM) - light brown, moist, fine to coarse grained, cobbles up to 8" diameter, rounded to subrounded, low plasticity.

0-2" Asphalt 2"-8" Base

8"-1.5' GRAVEL with silt and sand (GP-GM) - light brown, moist, fine to coarse grained, cobbles up to 8" diameter, rounded to subrounded, low plasticity.

0-2" Asphalt 2"-8" Base

8"-2' GRAVEL with silt and sand (GP-GM) - light brown, moist, fine to coarse grained, cobbles up to 8" diameter, rounded to subrounded, low plasticity.

Biaxial Geogrid and non-woven geotextile at bottom f b18 3474+00 L 12 Biaxial Geogrid and non-woven geotextile at bottom of base

19 3475+50 L 12 Biaxial Geogrid and non-woven geotextile at bottom of base 20 3477+50 L 12 Biaxial Geogrid and non-woven geotextile at bottom of base 21 3865+00 L Base extends full depth to 13' from CL, tapers to 17 ' from CL 22 3875+75 R No significant base. New sewer line buried in shoulder.

Cottonwood Pass East Side Field Observations Date: 10/5/2016

TABLE

Near low spot in ditch, add additional drainage provisions?

1 3126+00 R 1

2 3127+50 R 1

3 3148+00 R 2

4 3179+00 R 3

5 3195+00 L 4

6 3197+00 R 4

10 3316+50 L 7

11 3318+00 R 7

L 8

14 3347+00 L 10

17 3469+50 L 12

Running water at right side of embankment, wetland

Contractor to pot hole prior to construction?

15 3458+00 L 11?

16 3463+00 R 11?

12 3322+50

APPENDIX B – Pavement Assessment Photos

Typical Edge Cracking – Random Throughout the Route

Typical Transverse, Longitudinal, and Block Cracking along Route

Typical Block and Alligator Cracking along Route

Typical Block Cracking along Route

2’ Thick Layer of Topsoil beneath Road – Typical for Most Test Pits

Fabric and Geogrid Approximately 8” Below Existing HACP

Inadequate Ditch Maintenance at Many Locations along Route

Core Drilling Operation to Confirm Asphalt and Base Thickness (July 2017)

APPENDIX C – Excerpts from 1982 Material Investigation

APPENDIX D – Excerpts from 1987 Material Investigation

APPENDIX E – Excerpts from 1996 Materials Report

APPENDIX F – Pavement Design Calculations

Rigorous ESAL Calculations

Project: CO FLAP CHA 306(1) Date: 10/3/2017 Location: Cottonwood Pass East Side

Cottonwood Pass ESAL Calculation

Performance Period (years) 20 Two-Way Traffic (ADT) 1000 Number of Lanes in Design Direction 1 Percent of Trucks in Design Lane 100% Percent of Trucks in Design Direction 60%

Accumulated Average Initial 18-kip ESALs for

Vehicle Percent Annual % Growth Truck Factor Performance Class of ADT Growth Factor (ESALs/Truck) Period

2-3 88% 2% 24.30 0.004 18,730 5 10% 2% 24.30 0.5 266,056 9 2% 2% 24.30 2 212,845

Total 497,632

Cottonwood Pass East Side, Chaffee County, Colorado

Pavement Design Structural Number (SN) Calculation

APPENDIX G – LTPPBind & Climate Data

BindReport-5Closest.txt

Five Closest Weather Stations For Latitude/Longitude= 38.845/106.622 Report Date: 9/24/2015 (LTPPBind V3.0 Alpha)

LTPPBIND Cottonwood Pass

General A=3 km B=29 km C=30 km D=38 km E=41 km Station ID CO8184 CO1959 CO6513 CO8501 CO1071 County/District gunnison gunnison gunnison lake chaffee Weather Station taylor park crested butte pitkin twin lakes rese buena vista Elevation, m 2608 2510 2606 2605 2246 Latitude, Longitude 38.82 ,106.62 38.87 ,106.97 38.6 ,106.53 39.1 ,106.35 38.85 ,106.13 Last Year Data Available 1997 1997 1985 1997 1997

Air Temperature Mean ( Std, N ) Mean ( Std, N ) Mean ( Std, N ) Mean ( Std, N ) Mean ( Std, N ) High Temperature 24.4 (12,35) 26.7 (13,33) 25.6 (8,21) 25.3 (13,26) 30.3 (12,32) Low Temperature -41.7 (43,35) -36.1 (36,34) -34.1 (29,20) -31.4 (43,18) -26.3 (35,33) Low Temperature Drop 36.8 (31,35) 32.4 (34,34) 29.7 (24,20) 31 (38,18) 29.9 (29,33) Degree-Days > 10C 1327 (141,35) 1614 (165,33) 1513 (125,21) 1442 (142,26) 2294 (166,32)

PG High Low Rel. High Low Rel. High Low Rel. High Low Rel. High Low Rel.

Pavement Temperature, C 40.1 -28.9 43.3 -24.8 42.2 -23.3 41.4 -21.5 50.3 -17.8 50% Reliability PG 46-34 (98,91) 46-28 (98,83) 46-28 (98,94) 46-22 (98,55) 52-22 (97,90) >50% Reliability PG 46-40 (98,98) 46-34 (98,98) 46-34 (98,98) 46-28 (98,95) 52-28 (97,98) = 46-34 (98,98) 58-28 (98,98)

TAYLOR PARK, COLORADO (058184)

Period of Record Monthly Climate Summary

Period of Record : 10/19/1940 to 01/21/2015

Percent of possible observations for period of record.

Max. Temp.: 99.4% Min. Temp.: 99.5% Precipitation: 99.5% Snowfall: 78.5% Snow Depth: 73.4% Check Station Metadata or Metadata graphics for more detail about data completeness.

Western Regional Climate Center, wrcc@dri.edu

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Annual Average Max.

Temperature (F) 26.8 31.9 38.0 45.9 56.3 67.3 71.8 69.4 63.5 53.3 38.5 27.9 49.2

Average Min.

Temperature (F) -10.5 -8.7 0.1 14.6 26.8 34.2 40.9 39.8 32.3 23.7 10.2 -5.5 16.5

Average Total Precipitation (in.) 1.36 1.29 1.44 1.38 1.32 0.97 1.84 1.83 1.40 1.31 1.26 1.40 16.81

Average Total SnowFall (in.) 22.8 16.8 18.7 11.2 2.8 0.2 0.0 0.0 0.2 3.3 12.6 21.1 109.6

Average Snow Depth (in.) 20 25 25 13 1 0 0 0 0 0 3 11 8

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TAYLOR PARK, COLORADO

Period of Record General Climate Summary - Temperature

Table updated on Oct 31, 2012 For monthly and annual means, thresholds, and sums:

Months with 5 or more missing days are not considered Years with 1 or more missing months are not considered

Seasons are climatological not calendar seasons

Western Regional Climate Center, wrcc@dri.edu

Station:(058184) TAYLOR PARK From Year=1940 To Year=2012

Monthly Averages Daily Extremes Monthly Extremes Max.

Temp.

Min.

Temp.

Max. Min. Mean High Date Low Date Highest Mean Year Lowest

Mean Year >= 90 F

32 F

32 F

0 F

F F F F dd/yyyy or yyyymmdd

F dd/yyyy or yyyymmdd

F - F - # Days

Days

Days

Days

January 26.8 -

10.5 8.2 54 24/1953 -56 13/1989 15.9 2000 -5.3 1984 0.0 22.9 31.0 23.3

February 31.9 -8.7 11.6 51 13/1979 -60 01/1951 18.9 2000 3.1 1987 0.0 14.5 28.2 20.4

March 38.0 0.1 19.0 61 31/2012 -42 03/1965 26.9 2004 7.4 1987 0.0 7.4 30.9 15.5

April 45.9 14.6 30.2 67 18/1954 -29 05/1945 38.8 2002 19.5 1984 0.0 1.7 29.7 3.6

May 56.3 26.8 41.6 82 26/1970 -5 08/1984 47.5 2000 32.6 1983 0.0 0.1 26.5 0.0

June 67.3 34.2 50.7 85 22/1954 15 14/1983 55.0 2012 44.5 1983 0.0 0.0 11.0 0.0

July 71.8 40.9 56.3 86 15/1942 20 28/1986 59.5 2003 48.9 1986 0.0 0.0 0.8 0.0

August 69.4 39.8 54.6 84 15/1964 17 13/1985 58.1 1969 49.2 1986 0.0 0.0 2.1 0.0

September 63.5 32.3 47.9 79 04/1960 4 30/1985 52.1 1997 39.1 1985 0.0 0.0 15.5 0.0

October 53.3 23.7 38.5 75 03/2010 -5 29/1980 44.4 2003 30.7 1984 0.0 0.5 28.1 0.1

November 38.5 10.2 24.4 65 04/1952 -30 27/1984 32.2 1949 15.0 1956 0.0 8.0 29.8 5.9

December 27.9 -5.5 11.2 57 01/1966 -53 10/1986 20.0 1980 0.6 1986 0.0 21.5 31.0 20.6

Annual 49.2 16.5 32.9 86 19420715 -60 19510201 36.2 2000 29.5 1983 0.0 76.6 264.5 89.5

Winter 28.9 -8.2 10.3 57 19661201 -60 19510201 16.3 2000 1.2 1987 0.0 58.9 90.2 64.4

Spring 46.7 13.8 30.3 82 19700526 -42 19650303 36.2 2012 21.7 1984 0.0 9.1 87.1 19.1

Summer 69.5 38.3 53.9 86 19420715 15 19830614 56.9 2012 48.3 1986 0.0 0.0 13.8 0.0

Fall 51.8 22.1 36.9 79 19600904 -30 19841127 41.4 1963 29.7 1985 0.0 8.6 73.4 6.0

Winter = Dec., Jan., and Feb. Spring = Mar., Apr., and May Summer = Jun., Jul., and Aug. Fall = Sep., Oct., and Nov.

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APPENDIX B – Pavement Assessment Photos