ANK TW A Extension - Addendum No. 1_2.19.25.pdf

Salida Airport – Harriet Alexander field

ANK Taxiway ‘A’ Extension Dibble Project No: 1019401.09

FAA AIP No: 3-08-0049-024/025-2025

Sponsor Project No: TBD

ANK Taxiway A Extension Addendum No. 1 Page 1

ADDENDUM No. 1

February 19, 2025

TO ALL PROSPECTIVE OFFERORS RESPONDING TO INVITATION FOR BID FOR CONSTRUCTION

OF THE Taxiway ‘A’ Extension project at the Salida Airport – Harriet Alexander Field, as outlined in the aforementioned Invitation For Bids (IFB) published on the Rocky Mountain E-Purchasing System

(www.bidnetdirect.com/colorado) on January 28th, 2025.

I. General

1. The Bidders are made aware that they must acknowledge receipt of all

Addenda (within the Contract Documents, Division I, Page B-2) as part of the bid submittal process. The Bidding Documents and subsequent addenda will be made available through BidNet Direct.

2. The Meeting Minutes and Attendance Sheet from the Pre-Bid Conference Meeting held on

February 11, 2025, at 10:00 am are attached.

3. All bids must be received electronically through BidNet Direct prior to 2:00 PM (MT) on

Thursday, February 27th, 2025.

4. TAX EXEMPTION: Article No. 18, on page CA-7 of the Contract Agreement with Chaffe

County, the City of Salida and Harrier Alexander Field – Salida Airport states:

Contractor acknowledges and understands that all materials, products and supplies used or consumed on the Project are exempt from state and local sales and use taxes and that such sales and use taxes shall not be included in any applications for payment. Contractor further acknowledges receipt of the County’s tax-exempt number for itself and all subcontractors and material suppliers associated with the Project

This article is binding and supersedes all other references to sales tax obligations for this project.

5. The Geotechnical Report for this project titled, Geotechnical Engineering Report – ANK

Salida Taxiway A Extension and Fuel Farm, dated August 19, 2024 is attached.

www.bidnetdirect.com/colorado john.cessar Image john.cessar Text Box 02/19/25

Dibble Project No: 1019401.09

ANK Taxiway A Extension Addendum No. 1 Page 2

II. Contractor’s Questions

Question 1: Testing of Material - Is testing of materials, e.g. subgrade densities, base course testing, asphalt testing, performed by Chaffee County?

Response: Terracon will be performing Quality Assurance (QA) testing on all materials. P-403 testing will be conducted out of Terracon’s Colorado Springs Laboratory. The Contract is fully responsible for all Quality Control (QC) testing as outlined in the Contract Documents and Technical Specifications. The Contractor cannot rely on any QA testing by Owner/Terracon for their QC testing.

Question 2: Tax Exemption – Is this project tax exempt?

Response : Yes. See General Item No. 4 (on page 1) of this addendum.

Question 3: Water Supply – Is there a water supply available and provided by the airport/Chaffee County?

Response: Refer to Division II, Special Provision, Section 50.02. The Contractor, at his expense, shall provide all water required for, and in connection with, the work to be performed.

It is the Contractor's responsibility to identify the water source and its compatibility, storage, and costs for all water requirements for this project.

Water sources are available through the City of Salida or the Town of Poncha Springs, from hydrants near the airport along CR 140. The contractor is responsible for coordinating the use of these water sources and paying fees for the water and any necessary equipment (i.e. meters, backflow preventers) necessary to utilize these water sources. The City of Salida also has a bulk water facility located approximately 2.3 miles from the airport.

Question 4: Excess Material – Can excess material be placed in a designated area within or near the project area?

Response: This project will be utilizing an on-site borrow area. Therefore, there should not be excess soil produced on this project. Any other waste material produced by the contractor (not dirt), shall be hauled off site and disposed of at the contractor’s expense.

Question 5: Borrow Pit Material – Will borrow pit material be provided by the Airport/Chaffee County?

Response: The Borrow Pit is located on Airport property next to the project site, as shown on Sheet G1.4 of the plan set.

Question 6: Bid Documents - The 'Buy American Certification' and 'Tax Delinquency & Felony Convictions Certification' forms are missing from the documents. They are needed for bid submittal. Are these going to be provided?

Response: The Buy American Certification and Tax Delinquency & Felony Convictions Certification forms are located in Division III, Federal Assurances as follows.

• Buy American Certification: Division III, Page FA-3-5

• Tax Delinquency & Felony Convictions: Division III, page FA-27

Dibble Project No: 1019401.09

ANK Taxiway A Extension Addendum No. 1 Page 3

Question 7: Bid Submittal - Directions state that the complete, intact proposal forms, contract documents, and specifications booklet must be submitted at bid time. There is nothing called this, but there is a document called 'ANK TW A Extension - Final Contract Docs/Tech Specs' that is 390 pages long. Do you want or require all 390 pages submitted? Please clarify.

Response: The entire contract documents and specifications booklet is not required to be submitted. As shown on Page SNTB-1, Special Notice to Bidders, the following documents are required to be submitted at the time of bid.

Each Bidder must complete, sign, and submit the above-listed Chaffee County documents with their bid to be considered a responsive, responsible, qualified and acceptable bid, at the time the bid documents are due.

Question 8: Project Sales Tax - The bid documents specifying the sales tax for the project are contradicting in multiple sections. Can you please confirm whether or not sales tax for this project is exempt for both state and local county/city?

Response: Yes. See General Item No. 4 (on page 1) of this addendum.

Salida Airport - Harriet Alexander Field (ANK)

Taxiway ‘A’ Extension (Phase 1) Dibble Project No: 1019401.09

Pre-Bid Conference Minutes ANK TW A Extension (Phase 1) Page 1

Pre-Bid Conference Minutes

Thursday, February 11th, 2025, at 10:00 A.M. (MT)

1. Conference Call-In Information:

a. Date/Time: Tuesday, February 11th, 2025, at 10:00 am (MT)

b. Toll number: (480) 378-0989

c. Conference ID: 685 409 279#

2. Project Team

a. Sponsor Staff Zech Papp Airport Manager Don Reimer Chaffee County, Administrator Beth Helmke Chaffee County, Deputy Director of Administration Christy Doon City of Salida, City Administrator

b. Engineer/Construction Administration John Cessar Dibble, Senior Project Manager Jenna LoBello Dibble, Senior Project Engineer Michael Swearingen Dibble, Assistant Engineer Kurt Dalton Dibble, Engineering Technician Jim Hodge Dibble, Project Coordinator Jared Bass Dibble, Aviation Group Leader Catherine Alcorn CR Engineers, President Shane Woodard CR Engineers, Inspector

3. Bidding Process and Timeline

a. Bid Advertisement…………………………………………….………..January 28th 2025

1. Advertised in the Rocky Mountain E-Purchasing System:

https://www.bidnetdirect.com/public/solicitations/4942092312/abstract

b. Non-Mandatory Pre-Bid Conference……………………………. February 11th, 2025, at 10:00 am (MT)

c. Last Day for Questions…………….………..……..………………… February 14th, 2025, at 3:00 pm (MT)

1. Any questions received after this date may not be answered.

2. All questions (excluding those asked during the Pre-Bid Conference) need to be submitted through BidNet Direct.

d. Final addenda (if needed) will be posted by………………….. February 20th, 2025.

e. Bid Deadline ………………………………………………………February 27th, 2025, by 2:00 pm (MT)

f. Anticipated Award of Contract (Bid Hold).…………………… 120 Calendar Days

g. Bid Submittal Location:

1. Electronically submitted on Bidnet Direct.

h. Bid Bond: …………………………………………………………………..5% of total bid

i. All Addenda must be acknowledged and included in Bid Submittal at the time of Bid.

Acknowledgement location is in Division I, page B-2, Section 8.

j. Bid Schedule included in Division I, pages B-5 thru B-9.

https://nam02.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.bidnetdirect.com%2Fpublic%2Fsolicitations%2F4942092312%2Fabstract&data=05%7C02%7Cjohn.cessar%40dibblecorp.com%7C64c42b80c65c4945c37308dd3c9162a8%7Ce978d1e4af314393aa9f7e93edc74670%7C0%7C0%7C638733317306405606%7CUnknown%7CTWFpbGZsb3d8eyJFbXB0eU1hcGkiOnRydWUsIlYiOiIwLjAuMDAwMCIsIlAiOiJXaW4zMiIsIkFOIjoiTWFpbCIsIldUIjoyfQ%3D%3D%7C0%7C%7C%7C&sdata=B3PF08YXuPHBOffbLlEgFQ6apedYc06fodlINTNXk5U%3D&reserved=0

Pre-Bid Conference Minutes ANK TW A Extension (Phase 1) Page 2

4. Project Overview

a. This project will be funded, in part, by a grant from the Federal Aviation Administration (FAA), a grant from the Colorado Department of Transportation (CDOT) Aeronautics Department, and local funds from Chaffee County.

b. Project Scope of Work:

• Base Bid: Construction of approximately 2,050 feet of additional Taxiway A, and a new connector Taxiway A5 to Runway 6-24.

▪ Civil

• Construct asphalt pavement sections (excavation, site grading, placement of base course, new asphalt section)

• Grading and drainage

• Pavement markings

• Seeding

▪ Electrical

• Install new LED Airfield Signage for the new Taxiway A5 connector

• Lower existing electrical feeder duct bank under the new Taxiway A5 connector.

• Install new edge reflectors

c. Total Project Time – 93 Calendar Days (reference attached Airport Site Plan):

• Phase 1A - 90 Calendar Days (Base Bid): Phase 1A will consist of the construction of approximately 2,050-feet of new structural taxiway pavement east-northeast of the existing Taxiway A. Construction operations will include excavation and grading, placement of the base course, construction of the new asphalt pavement section, installation of new airfield guidance signs and taxiway edge reflectors, as well as the application of temporary pavement markings.

• Phase 1B – 28 Calendar Days (Concurrent w/ Phase 1A): Phase 1B will consist of the modifications to the existing Taxiway A4 geometry and tie-in to existing Taxiway A, as well as the construction of the first portion of Taxiway A5. Phase 1B will be constructed concurrently with Phase 1A. Construction operations will include excavation and grading, placement of the base course and asphalt pavement section, installation of new airfield guidance signs and taxiway edge reflectors, as well as the application of temporary pavement markings

• Phase 1C – 10 Calendar Days (Concurrent w/ Phase 1A): Phase 1C will consist of the closure of Runway 6-24 and construction of Taxiway A5. Phase 1C will be constructed concurrently with Phase 1A. Construction operations will include earthwork, placement of the base course and asphalt pavement section, installation of new airfield guidance signs and taxiway edge reflectors, as well as the application of temporary pavement markings.

• Stop Period – 24 Calendar Days: There will be a 24-calendar day stop period between application of the temporary taxiway pavement markings and the permanent pavement marking application in Phase 2.

• Phase 2 – 3 Calendar Days: Phase 2 will consist of the application of permanent markings on Taxiways A, A4, and A5, including all lead-on/lead-off markings and centerlines leading to Taxiway A from and Runway 6-24.

Pre-Bid Conference Minutes ANK TW A Extension (Phase 1) Page 3

5. Liquidated Damages (Reference Federal General Provisions, Section 80-08)

Phase Description Liquidated

Damages

Allowed

Construction Time

Phase 1A TW A Extension $500/Day 90 Calendar Days

Phase 1B TW A4 Modification & TW A Tie-in $500/Day 28 Calendar Days

(Concurrent w/ Phase 1A)

Phase 1C TW A5 Construction $500/Day 10 Calendar Days

(Concurrent w/ Phase 1A)

Phase 2 Permanent Pavement Markings $500/Day 3 Calendar Days

6. Bid Documents

a. Reference Instructions to Bidders, pages IB-1 thru IB-3.

b. Bid Schedule in Division 1, Bid Proposal, pages B-5 thru B-9. Pay close attention to the measurement and payment sections of the following:

• Division II, Special Provisions

• Division V, Federal General Provisions

• Division VI, Federal Technical Specifications

• There are some construction work items and materials that are considered incidental to the project or other Bid Items. All potential bidders should conduct a close review of the project plans and technical specifications.

7. Special Requirements

a. All forms listed in Division I, Special Notice to Bidders (items (a.) through (n.) must be completed and submitted at time of bid.

i. List of Items required at time of Bid:

A. Non-Collusion Affidavit: Bidder Information, page NCA-1

B. Completed Bid Proposal – Schedule of Bid Items: Division I, page B-5 thru B-9

C. Bid Bond: Division I, page BB-1

D. Attachment A – List of Subcontractor & DBE Utilization (0.1% DBE Goal), Division I, page SUB-1

E. Attachment B – Letter of Intent to Perform as DBE Subcontractor: Division I, Page DBE-1

F. Attachment C – Identification Statement for DBE: Division I, page DBE-3

G. Attachment D – Demonstration of Good Faith Efforts: Division I, page DBE-5

H. Prequalification Form: Division I, page PF-1

I. Contractor’s Questionnaire: Division I, page CQ-1

J. Authorized Signature Form: Division I, page AS-1

Pre-Bid Conference Minutes ANK TW A Extension (Phase 1) Page 4

K. Certificate of Insurability: Division I, page CIS-1

L. Acknowledgement of any and all Addenda: Division I, page B-2, Section 8

M. Buy American Certification: Division III, Page FA-3-5

N. Tax Delinquency & Felony Convictions: Division III, page FA-27

8. Airfield Safety and Security

a. Review Division II, Special Provisions, Section 60.

1. Airport security requirements

2. Construction vehicle requirements

3. Barricade requirements

b. Contractor is required to provide a Safety Plan Compliance Document (SPCD) at the very beginning of the project prior to start of construction, reference Appendix A – Construction Safety and Phasing Plan for items to be addressed by SPCD.

9. General Construction Items

a. Mobilization:

1. Refer to Division VI, Federal Technical Specifications, Item C-105.

2. Mobilization is limited to 8% of the total bid, (Division V, Federal General Provisions, Section 20-03).

10. Addenda

a. At least one Addendum will be issued after the Pre-Bid Conference that will include the meeting minutes to the Pre-Bid Conference, answers to contractor questions to date, and any changes or updates to the plans and contract documents.

b. All Addenda will be posted on BidNet Direct. It is the full responsibility of any bidder wishing to submit a bid to obtain and acknowledge all addenda.

c. All Addenda must be acknowledged by the Bidder at the time of bid within their respective Bid Package submitted before the established deadline.

11. Bidder Questions

a. Question: Are escorts required along the Contractor’s Haul Route?

Answer: Escorts are not required. In addition, a gate guard will not be required. It will be the contractor’s responsibility to ensure that the access gate is closed when not in use, to prevent wildlife and unauthorized personnel from entering through the gate.

b. Question: Who is being used for QA material testing, and will they have a lab onsite?

Answer: Terracon will be performing QA testing. P-403 testing will be conducted out of Terracon’s Colorado Springs Laboratory.

Pre-Bid Conference Minutes ANK TW A Extension (Phase 1) Page 5

c. Question: How soon will QA test results be available after?

Answer: The intent is to have QA test results available the following morning prior to the next day’s paving operations.

d. Question: Is the tack coat required to be diluted?

Answer: Refer to Technical Specification P-603 “Emulsified Asphalt Tack Coat” in the Contract Documents for all tack coat requirements.

e. Question: Is proctor information available for the borrow material?

Answer: Proctor information material is included in the Geotechnical Report which is attached to this addendum. Soil borings were not taken directly in the borrow pit area, but adjacent to the borrow pit location. Based on historical geotechnical information, the borrow pit soil strata is consistent with the strata documented in the adjacent borings.

f. Question: Is there a water supply which can be used for moisture conditioning of materials?

Answer: Refer to Division II, Special Provision, Section 50.02. The Contractor, at his expense, shall provide all water required for, and in connection with, the work to be performed. It is the Contractor's responsibility to identify the water source and its compatibility, storage, and costs for all water requirements for this project.

Water sources are available through the City of Salida or the Town of Poncha Springs, from hydrants near the airport along CR 140. The contractor is responsible for coordinating the use of these water sources and paying fees for the water and any necessary equipment (i.e meters, backflow preventers) necessary to utilize these water sources. The City of Salida also has a bulk water facility located approximately 2.3 miles from the airport.

g. Question: Is this project tax exempt?

Answer: Yes. Article No. 18 on Page CA-7 of the Contract Agreement with Chaffe County, the City of Salida and Harrier Alexander Field – Salida Airport states:

Contractor acknowledges and understands that all materials, products and supplies used or consumed on the Project are exempt from state and local sales and use taxes and that such sales and use taxes shall not be included in any applications for payment. Contractor further acknowledges receipt of the County’s tax exempt number for itself and all subcontractors and material suppliers associated with the Project

This article is binding and supersedes all other references to sales tax obligations for this project.

h. Question: Will the P-403 mix design require the Asphalt Pavement Analyzer (APA) test?

Answer: The Asphalt Pavement Analyzer test will NOT be required as this project will be constructed for aircraft under 60,000 lbs.

Pre-Bid Conference Minutes ANK TW A Extension (Phase 1) Page 6

i. Question: Is there a site to dispose of excess waste material.

Answer: This project will be utilizing an on-site borrow area. Therefore, there should not be excess soil produced on this project. Any other waste material produced by the contractor (not dirt), shall be hauled off site and disposed of at the contractor’s expense.

j. Question: Will the Taxiway A Extension project take place at the same time as the New Fuel Farm project?

Answer: General Phasing Note No. 1 on Sheet G2.0 states, “Construction of the New Fuel Farm is expected to begin prior to the Taxiway A Extension project. If projects overlap, contractors will be required to coordinate scheduling and work zone details.”

Dibble Project No: 1019104.09

Salida Airport – Harriet Alexander Field (ANK) Page - 1 TW A Extension (Phase 1) - Pre-Bid Meeting

Pre-Bid Meeting Attendee List

Project: Salida Airport – Harriet Alexander Field: Taxiway A Extension

Date: February 11th, 2025 Time: 10:00 AM MST

Location: Salida Airport Terminal & Remote Conference Call

NAME (PRINT) REPRESENTING PHONE E-MAIL

Zech Papp – In Person ANK Airport 719-539-3720 zpapp@chaffeecounty.org

Daniel Tom Chaffee County 719-530-5591 dtom@chaffeecounty.org

Beth Helmke Chaffee County 719-539-2218 bhelmke@chaffeecounty.org

Christine Doon City of Salida 719-539-4555 christy.doon@cityofsalida.com

Paulette Lugo FAA 303-342-1256 paulette.lugo@faa.gov

Kaitlyn Westendorf CDOT 303-512-5258 kaitlyn.westendorf@state.co.us

John Cessar – In Person Dibble 720-399-9783 john.cessar@dibblecorp.com

Jenna LoBello - Virtual Dibble 602-957-3888 jenna.lobello@dibblecorp.com

Kurt Dalton - Virtual Dibble 720-598-2211 kurt.dalton@dibblecorp.com

Jim Hodge - Virtual Dibble 720-248-0853 jim.hodge@dibblecorp.com

Mike Swearingen - Virtual Dibble 720-399-9796 mike.swearingen@dibblecorp.com

Catherine Alcorn CR Engineers 480-816-5541 calcorn@creng.com

Shane Woodard CR Engineers 480-816-5541 swoodard@creng.com

Dibble Project No: 1019104.09

Salida Airport – Harriet Alexander Field (ANK) Page - 2 TW A Extension (Phase 1) - Pre-Bid Meeting

NAME (PRINT) REPRESENTING PHONE E-MAIL

Shane Lance - Virtual Pro Electric 970-250-4825 proelectrical.shane@gmail.com

Chip Reinhard - Virtual Electrical Excellence 719.635.8828 chip@einc.co

Stan Bistline - Virtual Elevated Excavating 720-666-9868

Ethan Lance – In Person Pro Electric 970-589-5696 Elance58@gmail.com

Mike Dierks – In Person Pyramid Construction 719.291.6886 mdierks@pyramidconstructioninc.com

Tyler Davis - Virtual Meridian Contracting 970-209-3155 T.davis@meridiancon.net

Brock Leger – In Person Pyramid Construction 719.424.5724 bleger@pyramidconstructioninc.com

Jason Dody – In Person Pyramid Construction 719.491.3105 jdody@pryamidconstructioninc.com

Justin Vensel – In Person United Companies 970-852-7775 justin.vensel@unitedco.com

Troy Hanenberg – In Person United Companies 719-851-0086 troy.hanenberg@unitedco.com

Naresh Surigala – In Person JHL Constructors 720-500-4338 nsurigala@jhlconstructors

Monio Renteria – In Person JARCCO 719-505-6253 arenteria@jarrco.com

Alyssa Long – In Person United Companies 719-618-8752 alyssa.long@unitedco.com

ANK Salida Taxiway A Extension and Fuel

Farm

Prepared by:

795 East Factory Drive

St. George, UT 84790

Landmark Project No: 240329

Prepared for:

Attn: John Cessar, P.E.

Dibble & Associates Consulting

Engineers, Inc.

2696 South Colorado Blvd, Suite 330

Denver, CO 80222

August 19, 2024

GEOTECHNICAL

ENGINEERING

REPORT

8/19/2024

795 East Factory Drive, St. George, UT 84790 • Phone (435) 986-0566 • Fax (435) 986-0568

August 19, 2024

Dibble & Associates Consulting Engineers, Inc.

2696 South Colorado Blvd, Suite 330

Denver, CO 80222

Attn: John Cessar, P.E.

Sr. Project Manager

Subject: Geotechnical Engineering Report

ANK Salida Taxiway A Extension and Fuel Farm

Salida, Colorado

Landmark Project No. 240329

Mr. John Cessar, P.E.:

As requested, we have completed our Geotechnical Engineering Report for the above-mentioned project. Our services were conducted in general accordance with our proposal to you YP4813 dated January 25, 2024. The purpose of this report is to present the results of our field and laboratory testing and provide recommendations regarding the proposed Taxiway A Extension and

Fuel Farm.

Please feel free to contact our office at (435) 986-0566 if you have any questions.

Sincerely, LANDMARK TESTING & ENGINEERING

Kirk Jackson, P.E.

Senior Materials Engineer

Reviewed by:

Chad Hardman, P.E.

Professional Engineer

8/19/2024

Geotechnical Engineering Report i

TABLE OF CONTENTS

Geotechnical Engineering Report

ANK Salida Taxiway A Extension and Fuel Farm

Salida, Colorado

1.0 INTRODUCTION

2.0 PROPOSED CONSTRUCTION

3.0 SITE CONDITIONS

3.1 EXISTING ASPHALT SURFACE CONDITIONS

3.2 GEOLOGIC SETTING

3.3 GEOLOGIC HAZARDS

3.4 SEISMICITY

4.0 FIELD EXPLORATION

4.1 FIELD EXPLORATION

4.2 LABORATORY TESTING

4.3 GEOTECHNICAL SUBGRADE CHARACTERIZATION

5.0 SITE GRADING AND EARTHWORK

5.1 GENERAL GRADING

5.2 FILL PLACEMENT AND COMPACTION

6.0 FOUNDATION & CONSTRUCTION CONSIDERATIONS

7.0 SOIL CORROSIVITY

8.0 AIRFIELD PAVEMENT DESIGN CONSIDERATIONS

8.1 PAVEMENT SUBGRADE SUPPORT CHARACTERISTICS

8.2 DESIGN AIRCRAFT FLEET MIX

8.3 OTHER PAVEMENT DESIGN CONSIDERATIONS

8.4 PAVEMENT THICKNESS DESIGN RECOMMENDATION

8.5 PAVEMENT CLASSIFICATION RATING

9.0 MATERIAL SPECIFICATION RECOMMENDATIONS

9.1 SUBGRADE

9.2 SUBBASE AND AGGREGATE BASE COURSE

9.3 ASPHALT SURFACE COURSE

10.0 LIMITATIONS

ii

TABLE OF FIGURES

Geotechnical Engineering Report

Salida, Colorado

APPENDIX A – Field Exploration

FIGURE A-1: Vicinity Map

FIGURE A-2: Site Map

FIGURE A-3: Unified Soil Classification System

FIGURES A-4 through A-16: Boring Logs B-01 to B-03, and B-05 to B-

FIGURES A-13 through A-19: Dynamic Cone Penetrometer (DCP) Test

Reports

APPENDIX B – Laboratory Test Results

FIGURES B-1 through B-7: Soil Classification Report

FIGURES B-8 through B-10: Proctor Report

FIGURES B-11 through B-13: California Bearing Ratio

FIGURES B-14 through B-17: Moisture Content Report

FIGURE B-18: Water-Soluble Sulfate in Soil

FIGURE B-19: Summary of Laboratory Test Results

APPENDIX C – Supporting Information

FIGURES C-1 through C-3: ASCE Hazards Report

FIGURES C-4 through C-14: FAARFIELD Calculations

FIGURE C-15: PCASE Pavement Frost Design

Calculations

FIGURE C-16 and C-17: GBA Important Information About This

1.0 INTRODUCTION

This report presents the results of Landmark Testing & Engineering’s (Landmark) geotechnical exploration for the ANK Salida Taxiway A Extension and Fuel Farm project in Salida, Colorado.

The purpose of these services is to provide information and geotechnical engineering recommendations related to:

Subsurface soil conditions

Groundwater conditions

Frost considerations

Site grading and earthwork recommendations

Foundation and construction recommendations

Airfield pavement design considerations

The scope of services for this project included the advancement of 9 borings to 10 feet below existing site grades or to auger refusal. Figure A-1 is a Vicinity Map showing the project location relative to surrounding features. Figure A-2 is a Site Map showing the proposed project layout and the approximate locations of the borings completed for this project.

2.0 PROPOSED CONSTRUCTION

Our understanding of the proposed construction is based on the information provided in your email. We understand from your email the preliminary plan is to extend the existing Taxiway A from the existing pavement another approximate 1,800 feet, and the construction of a new taxiway connector. The project also includes the construction of a fuel farm near the existing hangar buildings. The estimated design fleet mix has been provided to us by Dibble.

3.0 SITE CONDITIONS

3.1 EXISTING ASPHALT SURFACE CONDITIONS

Prior to the advancement of the borings, the existing asphalt at Boring B-01 and B-09 was cored, and the cores were transported to the Landmark St. George laboratory for thickness measurements and observations. A summary of the existing asphalt thickness and associated pavement layers observed during drilling is provided in the following table:

Table 1 Summary of Existing Asphalt Core and Base Course Thicknesses

Boring Asphalt Core

Thickness (in)

Base Layer

Thickness (in)

Subbase Layer

Thickness (in)

B-01 4 ½ 8 12

B-09 8 11 12

Landmark also observed and documented the existing pavement conditions and distresses during our field exploration. The general condition of the existing pavement, including the general frequency and severity of distresses, were documented near and between the boring locations. The general distresses observed are as follows:

Longitudinal and Transverse Cracking: Longitudinal and transverse cracks are generally formed due to stresses induced from temperature fluctuations in the pavement. As asphalt ages, the pavement becomes more susceptible to such cracking. Low severity longitudinal and transverse cracking were observed to be extensive throughout the runway surface. Almost without exception, each of these cracks were filled with crack seal. Most of the cracks observed were longitudinal cracks associated with the joints of apparent paver passes. Transverse cracks were generally low severity cracks and were crack sealed.

Weathering: Weathering of the asphalt pavement refers to the effects of long-term exposure to environmental conditions on the asphalt surface. It is a natural process that can lead to the degradation of asphalt pavement over time. The most significant factor influencing the rate of weathering is the prolonged exposure to ultraviolet

(UV) radiation from the sun. The continuous exposure to sunlight accelerates the aging process of asphalt, making it more prone to various distresses, including cracking and surface raveling. Regular maintenance such as the application of seal or fog coats can help protect the asphalt surface from the effects of weathering. The observed weathering was low severity.

The existing condition of the asphalt taxiway and connectors is generally good to excellent. It appears general maintenance, such as crack sealing and fog coats, was performed to preserve the pavement. The longitudinal and transverse cracking and weathering observed are typical for the age of the pavement and are likely associated with age and weather. Structural related distresses such as alligator (fatigue) cracking or rutting were not observed.

3.2 GEOLOGIC SETTING

According to the Geological Survey Professional Paper 829,1 the project site is mapped as located on the border of two formations primarily:

Qgo: Older Alluvium and Outwash (Quaternary) - Sand, silt, clay, and gravel deposited in valleys. Predominantly alluvial deposits consisting of fine- grained over bank deposits (clay and silt) and coarse-grained stream channel deposits (sand and gravel). This unit underlies floodplains, stream terraces, and alluvial fans.

Td: Dry Union Formation (Tertiary) – White, gray, tan, and pink clay, silt, sand, and gravel;

locally tuffaceous and bentonitic; includes flood-plain, alluvial-fan, pond, mudflow, and volcanic ash deposits.

3.3 GEOLOGIC HAZARDS

Landslides

The site is shown on the Colorado Geologic Survey: hazards map as being located partially within a moderate landslide hazard area. Geologic units that crop out on the slopes above a determined critical angle of 14 degrees are considered to have a moderate landslide hazard.

Fault Rupture

There is a trace fault system located approximately 3 miles to the southwest of the project area.

The U.S. Geological Survey indicates that the north/northeast-trending normal fault zone cuts an erosion surface formed on Paleozoic rocks between the Weldon Gulch and Salida. The faults are west of Poncha Springs. Faults have vertically displaced Paleozoic strata by as much as 60 m, forming southeast-facing escarpments and narrow grabens with gentle to steep slopes. Based on their strong geomorphic expression, Quaternary activity is possible on some of these faults, but such movement has not been conclusively demonstrated.

The fault zone has been classified as undifferentiated Quaternary (<1.6 million years old). This timing estimate is very poorly constrained, but the strong geomorphic expression of some fault scarps suggests that there has been some Quaternary activity on this fault system. Low slip-rate category assigned based on the lack of demonstrable evidence for Quaternary movement shows

1 Van Alstine, R.E., 1974, Geology and mineral deposits of the Poncha Springs SE quadrangle, Chaffee

County, Colorado, U.S. Geological Survey, Professional Paper 829, 1:24,000. Accessed July 9, 2024.

https://ngmdb.usgs.gov/mapview/?center=-106.011,38.539&zoom=14 that the potential for surface fault rupture is considered low.

3.4 SEISMICITY

Seismicity at the site was determined using the American Society of Civil Engineers2 (ASCE)

Seismic Hazard Tool in accordance with ASCE 7-16. The following values are presented to assist with seismic design:

• Latitude = 38.534197° North, Longitude = 106.05886° West

• Site Class = D - Stiff Soil, based on ASCE 7 as referenced in 2021 IBC

Table 2 Summary of ASCE Seismic Design Parameters

Period (sec) Sa (g) Site Class

0.2 SS = 0.335 B/C

1.0 S1 = 0.094 B/C

0.2 SDS = 0.342 D

1.0 SD1 = 0.15 D

As per Section 20.1 of ASCE 7-16, “The soil shall be classified in accordance with Table 20.3-1 and Section 20.3 based on the upper 100 feet of the site profile.” However, Section 20.1 continues, “Where site specific data are not available to a depth of 100 feet, appropriate soil properties are permitted to be estimated by the registered design professional preparing the soil investigation report based on known geologic conditions.” Based on our engineering experience in the area, mapped geology and the soils encountered in the test pits, it is the opinion of Landmark Testing and Engineering that the soils on site classify as Site Class D – Stiff Soil. The full ASCE Hazards

Report is included in Appendix C.

4.0 FIELD EXPLORATION

4.1 FIELD EXPLORATION

The field exploration included the advancement of 9 borings to depths of approximately 10 feet or auger refusal. In Boring B-01 and B-09, the existing asphalt pavement was cored, and the cores were prepared for transport to the Landmark St. George laboratory for further evaluation and

2 American Society of Civil Engineers, ASCE 7 Hazard Tool, https://asce7hazardtool.online/, Accessed July 9, 2024.

https://asce7hazardtool.online/ testing. The borings were advanced with a CME 75 truck mounted drill rig utilizing 6.0-inch O.D.

solid-stem augers. Care was exercised to avoid doming of the pavement surrounding the boreholes.

Samples were obtained with a 2.5- inch O.D., split barrel, sampler driven with a 140-lb auto hammer dropping 30 inches. Depending on subsurface conditions, bulk samples of soils were obtained from the auger cuttings. The approximate locations of the borings are shown on Figure

A-2 Site Map.

Dynamic cone penetrometer (DCP) tests were performed at each location outside of the existing asphalt pavement in general accordance of ASTM D6951 Standard Test Method for Use of the

Dynamic Cone Penetrometer in Shallow Pavement Applications.

A Landmark geotechnical engineer supervised the drilling, prepared field logs of the subsurface condition, and prepared the samples for transport. The samples were transported to the Landmark

St. George laboratory where a geotechnical engineer reviewed the field logs and samples and assigned the samples for laboratory testing. The results of the laboratory testing were used to finalize the preliminary field soil classifications. A key to the soil classifications used on the logs is presented on Figure A-3 Unified Soil Classification System. The final boring logs are presented on Figures A-4 through A-16.

Groundwater was not encountered during our field exploration.

4.2 LABORATORY TESTING

Soil samples from the test pits were taken to our St. George, Utah laboratory for testing. The laboratory tests were performed in general accordance with the referenced standards and included the following tests:

• ASTM D4318 Atterberg Limits

• ASTM D1883 California Bearing Ratio

• ASTM C136 / C117 Sieve Analysis

• ASTM D7928 Hydrometer Analysis

• ASTM D698 Standard Proctor

The results of the laboratory tests are shown on the Boring Logs on Figures A-4 through A-16.

Appendix B includes individual test results and a Laboratory Summary on Figure B-19.

4.3 GEOTECHNICAL SUBGRADE CHARACTERIZATION

Our field and laboratory tests results indicate the soils on site consisted of predominately dense to very dense silty or clayey sand with gravel soils. Auger refusal was encountered on dense cobbles and boulders at varying depths. A summary of the depth to refusal is presented in the following table:

Table 3 Approximate Depth to Auger Refusal

Boring

Depth to

Refusal

(ft)

Boring

Depth to

Refusal

(ft)

B-01 9 B-07 5

B-02a 3 B-08 --

B-02b 5.5 B-09 --

B-03 7 B-10a 6

B-05 -- B-10b 9

B-06 --

California Bearing Ratio

California Bearing Ratio (CBR) tests were performed in general accordance with ASTM D1883 on bulk samples taken from select borings. The CBR samples were compacted to between 95 and

100 percent of the maximum dry density as determined by ASTM D698 Standard Proctor method.

Correlations to in-situ CBR values were also obtained from the results of the DCP field tests. A summary of the CBR test results from the laboratory and DCP tests is provided in the following table:

Table 4 Summary of California Bearing Ratio Test Results

Boring

DCP Results Laboratory CBR Results

Depth (ft) Correlated CBR Depth (ft) Percent

Compaction

CBR

From To Min. Max. Avg. From To

B-02 0 2.1 24.0 76.7 35.3 0 7 97 15

B-03 0 2.2 15.6 50.4 33.6 -- -- -- --

B-04 0 2.2 13.1 100.0 47.8 -- -- -- --

B-05 0 1.5 14.3 100.0 74.5 -- -- -- --

B-06 0 2.1 10.4 100.0 45.0 0 10 96 29

B-07 0 2.1 17.7 100.0 44.8 -- -- -- --

B-08 0 2.1 12.5 39.3 23.1 0 10 99 34

More complete CBR test results are included in Appendix B.

Incidentally, the CBR tests also provide results for determining the swell potential of the subgrade soil in accordance with the AC 150/5320-6G Section 3.9.3. The following table lists the results of the swell potential based on the laboratory CBR testing of the subgrade soils.

Table 5 Summary of Laboratory CBR Swell Results

Boring Soil Classification

Compaction

Moisture

Content

Dry

Density

(pcf)

Swell

B-03 @ 0 - 7 Clayey Sand with Gravel 9.1% 123.2 -0.5%

B-06 @ 0 – 10 Silty Sand with Gravel 8.3% 130.4 -0.1%

B-08 @ 0 – 10 Silty, Clayey Sand with Gravel 7.6% 131.1 -0.1%

Frost Group

The results of the laboratory classification testing, in conjunction with the results of the hydrometer tests, can be used to determine the soil frost group in accordance with the Federal Aviation

Administration (FAA) Advisory Circular (AC) 150/5320-6G Table 2-2. The results of the hydrometer testing from select samples indicate percent finer than 0.02 mm of the onsite soils range from 8.3 to 9.4 percent. Based on these results, and the results of the laboratory gradation analyses, we recommend a frost group classification of FG-2 for the near surface onsite soils.

5.0 SITE GRADING AND EARTHWORK

5.1 GENERAL GRADING

Site preparation should initially consist of grubbing and removal of vegetation. Grubbing is expected to extend about 6 inches below the existing grade to remove root mat. This stripped material should not be used as structural fill on site and should only be used in non-structural areas.

The subgrade should be excavated to 6 inches below the bottom of footings or slab on grade. The subgrade to receive footings or the slab on grade should be free of standing water, frozen material, loose, soft or otherwise unsuitable material. Loose or soft areas of the exposed subgrade should be reworked until the entirety of the prepared subgrade is firm and unyielding.

The footings and slab on grade should be supported on a minimum of 6-inches of imported granular fill. The inclusion of the imported granular fill beneath the footings and slab on grade will disperse point loading from the coarse cobbles and boulders, provide additional structural support to obtain the recommended bearing capacity, and increase the drainage capacity beneath the structure.

5.2 FILL PLACEMENT AND COMPACTION

All fill to be placed for support of footings and slabs-on-grade should be considered structural fill.

On-site soils are suitable for use as structural fill. Imported granular fill, should be well-graded, non-expansive, and free of organics and all deleterious materials. Soils used for imported, granular fill should meet the following specifications and preferably would classify as gravel.

Table 6 Import Granular Fill Specifications

Gradation Percent Passing

6- inch 100

3-inch 80-100

No. 200 sieve 10-25

Atterberg Limits

Liquid Limit 30 or less

Plasticity Index 9 or less

Material not meeting the above requirements may be suitable for use as structural fill at the discretion of the geotechnical engineer. Samples of structural fill should be submitted for testing prior to transporting to the site.

Any on-site soils used as structural fill or imported, granular fill or aggregate base course should be compacted to the following specifications.

Table 7 Structural Fill or Imported Granular Fill Compaction Specifications

Fill Placement and Compaction

Maximum lift thickness 8-inch (loose)

Minimum compaction 95% ASTM D698

Compacted Moisture Content within 2% of optimum

Compaction of structural fill should be completed with equipment suitable for the conditions encountered in the field such that compaction requirements are met, including those areas that may be inaccessible to large rolling compactors. All structural fill should be evenly spread on a horizontal plane in a minimum of eight-inch loose lifts. Each lift of structural fill material placed at the site should be tested for compliance with the required relative compaction and moisture content prior to proceeding with additional lifts.

6.0 FOUNDATION & CONSTRUCTION CONSIDERATIONS

The proposed fuel farm may be supported on conventional spread or continuous footings established on subgrade prepared in accordance with the Site Grading and Earthwork recommendations in this report. Foundation excavations should be visually observed and tested by qualified personnel prior to placement of reinforcing steel or concrete. Additional foundation recommendations are subsequently presented.

Table 8 Summary of Foundation Recommendations

Description Value

Foundation Type Continuous or spread footings

Bearing Material 6 inches of compacted aggregate base course compacted to 95 percent of ASTM D698

Allowable Bearing Capacity 5,000 psf on structurally placed soils

Minimum embedment depth below finished grade 24 inches (per Chaffee County for frost and confinement)

Minimum footing width 12-inches

Total estimated settlement <1-inch

Total differential settlement less than 3/4 inch

The allowable bearing capacity is based upon dead load plus long-term live load. A one-third increase in allowable bearing capacity for short duration loads such as wind or seismic loads is permitted with the alternative load combinations given in Section 1605.3.2 of the IBC.

7.0 SOIL CORROSIVITY

Soils from the project site were tested for water-soluble sulfates content. The percent of water-soluble sulfates in a sample taken from B-10 at 0 to 5 feet was determined to be 0.17 percent which is considered low to moderate corrosive potential according to ACI 318. We recommend that concrete mixes used on the project be designed in accordance with ACI 318 Table 19.3.1.1 for

Sulfate Exposure Class S1. We recommend that buried pipes be plastic (PVC or HDPE) instead of metal, where possible. We recommend Type II Portland cement be used for concrete on and below grade.

8.0 AIRFIELD PAVEMENT DESIGN CONSIDERATIONS

Pavement designs for the airfield pavements for this project were performed in general accordance with the procedures outlined in the Federal Aviation Administration (FAA) Advisory Circular

(AC) 150/5320-6G Airport Pavement Design and Evaluation and Appendix G of AC 150/5320-

5D Design of Subsurface Pavement Drainage Systems. Current FAA practice for design of pavements is based on the use of the FAA computer program FAARFIELD. Airfield pavement thickness design is influenced by the subgrade soil support characteristics, the traffic loading, as well as other environmental factors such as the proximity to groundwater and the depth of frost penetration. The following sections outline the design parameters used in the development of our recommended pavement layer thicknesses and provides our recommendations for pavement layer material selection.

8.1 PAVEMENT SUBGRADE SUPPORT CHARACTERISTICS

Our recommendations regarding the subgrade support characteristics for pavement design are based on the results of the geotechnical characterization and field exploration and laboratory test results, the requirements for design of airfield pavements in AC 150/5320-6G Airport Pavement

Design and Evaluation and the requirements for subsurface pavement drainage systems in AC

150/5320-5D Design of Subsurface Pavement Drainage Systems.

One of the most important subgrade design parameters is the subgrade strength or modulus. The subgrade strength was estimated from the results of laboratory moisture, density and CBR tests on samples of the subgrade soil. Based on the field and laboratory test results and based on our experience with soils similar to the project subgrade soils, Landmark recommends a design CBR of 10 be used in the FAARFIELD analysis. The field exploration and laboratory test results indicate the actual subgrade CBR is much higher than 10, however a design CBR of 10 is the practical upper limit of subgrade strength. Using higher design subgrade CBR values will result in unrealistic recommendations for subgrade compaction and will no longer result in decreases in the recommended pavement thickness. For this project, the minimum thickness of pavement is governed by the need to limit the detrimental effects of frost.

Based on the results of the field exploration and laboratory testing, we estimate the permeability of the subgrade soils to be higher than 20 feet per day. Considering the recommendations for frost design discussed in Section 5.3 Other Pavement Design Considerations, we estimate the thickness of aggregate base and subbase course will provide adequate subsurface drainage capacity for the pavement.

8.2 DESIGN AIRCRAFT FLEET MIX

Dibble has provided the estimated design aircraft fleet mix for pavement design as summarized in the following table:

Table 9 Design Aircraft Fleet Mix

Aircraft

MTOW

(lbs.)

Average

Annual

Growth

Operations

/ Year

Pilatus 10,450

4%

7,685

Beech Airliner 11,300 588

Citation II 14,800 501

We also understand ANK receives occasional passes of 30,000 lbs. to 60,000 lbs. single wheel loads (SWL). The forecasted pavement performance is highly influenced by passes of these heavier SWL. Pavement design analysis was performed using the design aircraft fleet mix and a separate analysis was performed including passes of 60,000 lbs. SWL in general accordance with the guidance in AC 150/5320-6G 3.12.6.4.

The expected pavement performance life using the design aircraft fleet mix is much greater than

20 years. This is due to the requirement to increase the total design thickness of the pavement for frost considerations. The number of 60,000 lb. SWL that reduces the expected pavement performance life to 20 years was back calculated in FAARFIELD using the recommended pavement design thickness. Based on the FAARFIELD analysis, the pavement can theoretically support up to 172 passes per year of 60,000 lb. SWL without reducing the pavement design life below 20 years. The 172 passes per year of a 60,000 lb SWL is less than 2 percent of the expected operations per year.

8.3 OTHER PAVEMENT DESIGN CONSIDERATIONS

Structural thickness is not the only consideration for airfield pavement design. Pavement performance can be negatively influenced throughout the design life of the pavement by many factors such as subgrade swelling, frost heave, poor subgrade drainage, or inadequate material properties. The following sections provide a summary of the design considerations specific to this project based on the recommendations by the FAA publications cited herein.

Subgrade Swell Potential

Swelling soils are clayey soils which have the potential for volume change caused by variations in the moisture content of the subgrade. Swelling subgrade soils can cause differential heaving of the pavement surface leading to roughness and cracking. Pavement design strategies to address swelling subgrade soils depend primarily on two criteria: the swell potential of the soil type and the potential for moisture fluctuations. Based on the results of our field exploration and laboratory tests, the subgrade soils for this project exhibit a negligible risk for swelling soils.

Frost Considerations

The detrimental effects of frost action on pavement may include non-uniform heave and a loss of soil strength during the spring-thaw period. The AC 150/5320-6G provides three methods for designing pavements for frost action: Complete Frost Protection (CFP), Limited Subgrade Frost

Penetration, and Reduced Subgrade Strength (RSS). The depth of frost penetration for this project was estimated using the pavement design program PCASE using the following parameters as recommended in AC 150/5320-6G.

Table 10 Frost Design Parameters for Pavement Design

Parameter Value

Data from Weather Station Salida_Alexander

Air Freezing Index 202.3 degree-days

Mean Annual Temperature 49.82°F

Length of Frost Season 40.6 days

Using these parameters, PCASE estimated the frost depth to be 19 inches, however Chaffee

County recommends a minimum frost depth of 24 inches. The depth of frost was overridden in

PCASE to be 24 inches. The total thickness recommended by PCASE for limited subgrade frost penetration was less than 0.65 times the frost depth of 24 inches. We recommend the thickness of

P-154 be increased to the amount that the total pavement thickness is at least 16 inches. The

PCASE analysis is included in Appendix C.

Construction Considerations

Construction methods and materials should be specified in accordance with the Federal Aviation

Administration Advisory Circular (AC) 150/5370-10H Standard Specifications for Construction of Airports. Landmark respectfully requests the opportunity to review the final design drawings and specifications in order to determine whether the assumptions and recommendations presented herein are applicable to the anticipated designs.

8.4 PAVEMENT THICKNESS DESIGN RECOMMENDATION

Based on the results of our field exploration, laboratory testing, the requirements of AC 150/5320-

6G, and provided our recommendations are followed, the recommended pavement design thicknesses are listed in the following table:

Table 11 Pavement Thickness Design Recommendations

Material FAA Specification Item1 Thickness (in)

Asphalt Surface Course P-4032 4

Aggregate Base Course P-208 6

Subbase Course P-154 6

Total Thickness 16

1. See Section 6.0 Material Specification Recommendations for more details

2. CDOT 403 Hot Mix Asphalt, Grading S or SX, PG 64-28 may be substituted for

FAA P-403 as discussed in Section 6.3

In AC 150/5320-6G Table 3-3, the minimum asphalt surface course thickness for pavements supporting maximum aircraft gross weights of less than 60,000 lbs is 3 inches. Landmark recommends a minimum of 4 inches of asphalt surface course for the following reasons: to match the existing asphalt surface course thickness of the existing Taxiway A, allow for safe future 2-inch mill and overlay operations leaving 2 inches in place, and to accommodate occasional larger jet operations that may be anticipated in the future. More detailed FAARFIELD analysis reports are included in Appendix C.

8.5 PAVEMENT CLASSIFICATION RATING

Landmark performed preliminary analysis of the Pavement Classification Rating (PCR) of the proposed pavement section in general accordance with AC 150/5335-5D Standardized Method of

Reporting Airport Pavement Strength – PCR. The aircraft traffic fleet used in the PCR analysis was the same as which was used for the thickness design above. The analysis assumes the construction of the proposed pavement section will be in accordance with AC 150/5370-10H

Standard Specifications for Construction of Airports, and the…