Geotech Eng Report - El Vado and Heron Lake GEO Pavement Report_Signed.pdf

Geotechnical Engineering Report NM BR AOO El Vado

Heron & El Vado Road Rehabilitation

Heron Lake and El Vado Reservoir State Parks

Rio Arriba County, New Mexico

CFLHD Contract No. 6982AF19D000006

April 9, 2024

Terracon Project No. 66225032

Prepared for:

DJ&A, P.C.

Missoula, Montana

Prepared by:

Terracon Consultants, Inc.

Albuquerque, New Mexico

DJ&A, P.C.

200 Maple Street Missoula, Montana 59808

Attn: Ms. Jacquelyn Smith, P.E.

P: (406) 721-4320 E: MJacquelyn.Smith@djanda.com

Re: Geotechnical Engineering Report

NM BR AOO El Vado

Heron & El Vado Road Rehabilitation

Heron Lake and El Vado Reservoir State Parks

Rio Arriba County, New Mexico CFLHD Contract No. 6982AF19D000006

Dear Ms. Smith:

Terracon Consultants, Inc. (Terracon) has completed the geotechnical engineering services for the above referenced project. These services were performed in general accordance with DJ&A

Professional Services Agreements dated June 24, 2022 and August 4, 2023 under CFLHD Task

Order No. 6982AF23F00117N and CFLHD Contract No. 6982AF190D000006. This geotechnical engineering report presents the results of the subsurface exploration and provides geotechnical recommendations concerning pavements and earthwork for the proposed project.

We appreciate the opportunity to be of service to you on this project. If you have any questions concerning this report, or if we may be of further service, please contact us.

Sincerely, Terracon Consultants, Inc.

Laura Varone Michael E. Anderson, P.E.

Staff Engineer Principal

Copies to: Addressee (1 via email) https://na3.documents.adobe.com/verifier?tx=CBJCHBCAABAAeYhTZmtWa_HFaes0huAn3JlobELUB7eK

Heron & El Vado Road Rehabilitation ■ Rio Arriba County, NM April 9, 2024 ■ Terracon Project No. 66225032

TABLE OF CONTENTS

Page

EXECUTIVE SUMMARY ............................................................................................................. i

1.0 INTRODUCTION

2.0 PROJECT INFORMATION

2.1 Project Description

2.2 Site Location and Description

3.0 SURFACE AND SUBSURFACE CONDITIONS

3.1 Typical Surface and Subsurface Profile

3.2 Groundwater

4.0 RECOMMENDATIONS FOR DESIGN AND CONSTRUCTION

4.1 Geotechnical Considerations

4.2 Earthwork

4.2.1 Site Preparation

4.2.2 Excavation and Embankment

4.2.3 Subgrade Preparation

4.2.4 Materials and Placement

4.2.5 Compaction Requirements

4.2.6 Grading and Drainage

4.2.7 Corrosion Potential

4.3 Pavements

4.3.1 Design Recommendations

4.3.2 Materials Specifications

4.3.3 Pavement Maintenance

5.0 GENERAL COMMENTS

Appendix A – Field Exploration

Site Location Maps

Exploration Plans

Field Exploration Description

Boring Logs

General Notes

Unified Soil Classification System

Appendix B – Laboratory Testing

Laboratory Test Description

Atterberg Limits/Grain Size Distribution

Resistance Value (R-Value) of Compacted Soil

Summary of Laboratory Results

Appendix C – Traffic and Pavement Design Information

ESAL Calculations and AASHTO Pavement Design Thickness Spreadsheets

EXECUTIVE SUMMARY

This geotechnical executive summary should be used in conjunction with the entire report for design and/or construction purposes. It should be recognized that specific details were not included or fully developed in this section, and the report must be read in its entirety for a comprehensive understanding of the items contained herein. The section titled General Comments should be read for an understanding of the report limitations.

A geotechnical exploration has been performed for the proposed Heron & El Vado Road Rehabilitation Project located at Heron Lake and El Vado Reservoir State Parks in Rio Arriba County, New Mexico. Terracon’s geotechnical scope of work included the advancement of 25 test borings to approximate depths of 3 to 6.5 feet below existing site grades.

Based on the information obtained from our subsurface exploration, the site is suitable for the proposed rehabilitation/improvements. The following geotechnical considerations were identified:

Existing Pavement Thickness: The existing pavement section thickness along the existing roadway and parking areas are summarized below:

Location Asphalt Concrete (in.) Base Course (in.) 1

Heron Lake 2 N/A

El Vado 2 to 3 2,3 N/A

1. Base course was not encountered below the surficial pavement materials.

2. Two (2) inches of asphalt concrete encountered in two (2) borings

3. Approximately 2 inches of base course encountered at the ground surface in Boring No. B-01D and B-

01E at main parking lot and boat ramp

Subgrade Soils: The subgrade soils consisted predominantly of clay with varying amounts of silt, sand and gravel. Some silt layers with varying amounts of sand and gravel and sand layers with varying amounts of clay, silt, and gravel were encountered in some borings.

Auger refusal was encountered at depths ranging from about 3 to 5.5 below existing ground surface in some borings.

The subgrade soils classified as A-4, A-6, and A-7-6 in accordance with the AASHTO Soil Classification system. Groundwater was not encountered in any of the borings at the time of drilling. Based upon the AASHTO soil classifications and R-value test results, the majority of the subgrade soils are considered to be poor quality for roadway/pavement support.

Pavement Section: Based upon the limited thickness of existing pavement materials, reduce export and import of subgrade and pavement materials, and to maintain proposed grades near existing grades, it is our understanding that that the proposed new pavement section will consist of a new hot asphalt concrete pavement (HACP) surface over the existing pavement materials and subgrade following full depth reclamation (FDR) operations using cement stabilization. In addition, a crushed aggregate base (CAB) layer will be incorporated below the HACP surface layer within the recommended Heron Lake pavement sections to compensate for the thinner pavement section and higher traffic volumes.

The recommended pavement sections outlined below are considered the minimum sections based upon the traffic information provided (including large trucks, RVs, and trailers), estimated growth rate, poor quality subgrade soils, meeting a minimum 20-year design life, providing a durable pavement, and reducing future maintenance.

The recommended new pavement section thicknesses are summarized below:

Location Pavement Area Recommended Pavement Section (in.)

HACP 1 CAB 1 FDR 2,3

Heron Lake

Visitor Center Parking 4 3 4 N/A

Ridge Rock Access Road 3 2 4

Ridge Rock Parking 3 2 4

Narrows Boat Ramp

Access Road 3 2 4

Narrows Boat Ramp

Parking 3 2 4

El Vado State Park Road 5001 3 N/A 4

Parking 3 N/A 4

1. New pavement surface layers

2. Assumes a minimum of 4 inches of FDR using cement stabilization.

3. Preliminary estimated minimum cement content of 10%. Actual minimum cement content to be determined by mix design per the Specifications

4. Requires reconstruction to maintain existing grade constraints

Subgrade Stability: Elevated moisture contents and medium stiff soils were observed within the subgrade along portions of the project alignments. Therefore, during FDR operations, drying, mechanical stabilization, chemical stabilization, and/or replacement of these soils may be required to provide a stable platform for construction.

Earthwork on the project should be observed and evaluated by Terracon or a qualified geotechnical engineer.

The evaluation of earthwork should include observation and testing of engineered fill, subgrade preparation, and other geotechnical conditions exposed during construction.

GEOTECHNICAL ENGINEERING REPORT

NM BR AOO EL VADO

HERON & EL VADO ROAD REHABILITATION

RIO ARRIBA COUNTY, NEW MEXICO

CCFLHD CONTRACT NO. 6982AF19D000006

1.0 INTRODUCTION

This report presents the results of our geotechnical engineering services performed for the proposed

Heron & El Vado Road Rehabilitation Project located at Heron Lake and El Vado Reservoir State

Parks in Rio Arriba County, New Mexico. The purpose of these services is to provide information and geotechnical engineering recommendations relative to:

◼ Subsurface soil conditions

◼ Earthwork

◼ Pavement material specifications

◼ Groundwater conditions

◼ Reuse of existing pavement materials

◼ Pavement rehabilitation

◼ Pavement design and construction

◼ Concrete and metal corrosion potential

Our geotechnical engineering scope of work for this project included the advancement of 25 test borings to depths of approximately 3 to 6.5 feet below existing site grades along the project alignment.

Logs of the borings along with a Site Location Maps and Exploration Plans are included in Appendix

A of this report. The results of the laboratory testing performed on soil samples obtained from the site during the field exploration are included in Appendix B of this report. Descriptions of the field exploration and laboratory testing are included in their respective appendices.

2.0 PROJECT INFORMATION

2.1 Project Description

ITEM DESCRIPTION

Planned Project

The project will include improvements consisting of road and parking area rehabilitation and/or reconstruction, signing, striping, new curb and gutter, along with drainage improvements at two (2)

New Mexico State Parks.

Structures

The proposed improvements included in this study consist of the following:

◼ Heron Lake State Park o Visitors Center Access Drive and Parking o Narrows Boat ramp access Road and Parking o Ridge Rock Access Road and Parking

◼ El Vado Reservoir State Park o State Road 5001 o Main Parking Lot and Boat Ramp

Length of improvements

◼ Heron Lake = 0.52 miles (excludes parking areas)

◼ El Vado Reservoir = 4.35 miles (excludes parking areas) plus additional 0.36 miles from main parking lot to boat ramp

Cut and Fill Slopes At or near existing alignment grade

Slope configuration Not Applicable

Proposed pavement wearing surface

Hot asphalt concrete pavement (HACP) and crushed aggregate base (CAB) over full depth reclamation (FDR) with cement stabilization

Traffic data

The following traffic data were provided by the Bureau of

Reclamation (Albuquerque Office), Central Federal Lands

Highway Division (CFLHD), and DJ&A:

◼ Heron Lake annual visitors = 118,000

◼ El Vado annual visitors = 40,000

◼ Parking areas traffic = 10% of annual vehicles

◼ Class 5 vehicles = 25% (RVs, trailers, motorhomes, small buses, delivery trucks)

◼ Class 8 vehicles = 1% (semi-tractor trailer, large delivery trucks, trash trucks, large buses, large emergency response vehicles)

◼ 2% annual growth rate

◼ 20-year design

Specifications

2014 FP-14 Standard Specifications for Construction of Roads and

Bridges on Federal Highway Projects

2019 NMDOT Standard Specifications for Highway and Bridge

Construction

1993 American Association of State Highway and Transportation

Officials (AASHTO) Guide for the Design of Pavement Structures

2014 Federal Lands Highway (FLH) Project Development and

Design Manual

2.2 Site Location and Description

Location Heron Lake State Park and El Vado Reservoir State Park in Rio

Arriba County, New Mexico.

Existing improvements

◼ Heron Lake: Existing two-lane asphalt paved roadways with narrow paved shoulders and parking areas.

◼ El Vado Reservoir: Existing two-lane asphalt paved roadway with narrow paved shoulders. Gravel surfaced main parking area and boat ramp

Existing pavement condition

The pavement exhibits the following structural and climatic distress ranging from low to high severity:

◼ Alligator

◼ Potholes

◼ Patching

◼ Rutting

◼ Block cracking

◼ Longitudinal and transverse cracking

◼ Edge cracking

◼ Weathering

Existing pavement distress associated with drainage structures

◼ Drainage culvert at approximate Station No. 145+50

◼ Drainage culvert at approximate Station No. 152+20

Highway/road classification Low Volume Rural Road

Current ground cover

Paved and unpaved roadways and parking areas, along with exposed earth with vegetation common to the area located adjacent to the roadways.

Existing topography Roads and parking areas constructed on relatively flat to moderately sloping terrain.

3.0 SURFACE AND SUBSURFACE CONDITIONS

3.1 Typical Surface and Subsurface Profile

Specific conditions encountered at the boring locations are indicated on the individual boring logs.

Stratification boundaries on the boring logs represent the approximate location of changes in soil types; in-situ, the transition between materials may be gradual. Details for each of the borings can be found on the boring logs included in Appendix A of this report. Based on the results of the borings, subsurface soil conditions on the project site can be generalized as follows:

Heron Lake (Boring Nos. B-01A through B-01C, B-02B, B-03A, and B-04A):

Description Approximate Depth to

Bottom of Stratum (feet)

Material

Encountered Consistency/Density

Stratum 1 0.17 Asphalt Concrete – 2”

Base Course – N/A Not Applicable

Stratum 2 3 to 6.5 1 Lean to Fat Clay. The sand and gravel content varied Medium Stiff to Hard

Stratum 3 5 Sand. The silt and gravel content varied Dense to Very Dense

1. Auger refusal encountered in Boring Nos. B-01C and B-02B at depths of approximately 3 to 5 feet below existing ground surface

El Vado Reservoir (Boring Nos. B-01D and B-01E, B-02C, B-03B, B-04B, and B-05 through B-18

Description Approximate Depth to

Bottom of Stratum (feet)

Material

Encountered Consistency/Density

Stratum 1 0.17 to 0.25 Asphalt Concrete – 2” to 3”

Base Course – N/A Not Applicable

Stratum 2 4 to 6.5 1 Lean to Fat Clay and Silt. The sand and gravel content varied Medium Stiff to Hard

Stratum 3 5 Sand. The clay and gravel content varied Dense to Very Dense

1. Auger refusal encountered in Boring Nos. B-04B, B-06, B-07, B-09, and B-10 at depths of approximately 4 to

5.5 feet below existing ground surface

The subsurface sand and silt subgrade soils were non-plastic to medium in plasticity. The subsurface clay subgrade soils were low to high in plasticity.

The shallow subgrade soils are classified as outlined below:

Location Unified Soil Classification

System (USCS) AASHTO Soil Classification System

Heron Lake SM, CL, CH A-4, A-6, A-7-6

El Vado Reservoir SC, CL, CH, CL-ML, ML A-4, A-6, A-7-6

The near surface subgrade soils exhibit in-situ dry density and moisture contents ranging from about 71 to 121 pounds per cubic foot (pcf) and 0.9 to 22 percent, respectively.

The results of the R-value testing of the shallow subgrade soils are outlined below:

Boring No.

Unified Soil

Classification System

(USCS)

AASHTO Soil

Classification System R-Value

B-01C SM A-4 78

B-01E CL A-7-6 8

B-03A CH A-7-6 8

B-06 SC A-6 62

B-11 CL A-6 9

Laboratory tests are presented in Appendix B.

3.2 Groundwater

Groundwater was not observed in the test borings at the time of field exploration, nor when checked upon completion of drilling. These observations represent groundwater conditions at the time of the field exploration and may not be indicative of other times, or at other locations.

Groundwater conditions can change with varying seasonal and weather conditions, and other factors.

Fluctuations in groundwater levels can best be determined by implementation of a groundwater monitoring plan. Such a plan would include installation of groundwater monitoring wells, and periodic measurement of groundwater levels over a sufficient period of time.

4.0 RECOMMENDATIONS FOR DESIGN AND CONSTRUCTION

4.1 Geotechnical Considerations

The site appears suitable for the proposed improvements based upon geotechnical conditions encountered in the test borings.

The existing pavement section thickness along the project alignments varies from approximately

2 to 3 inches of asphalt concrete. Typically, two (2) inches of asphalt concrete was encountered at Heron Lake State Park and three (3) inches was encountered at El Vado Reservoir State Park.

Base course was not encountered below the pavement materials.

The subgrade soils consisted predominantly of clay with varying amounts of silt, sand and gravel.

Some silt layers with varying amounts of sand and gravel and sand layers with varying amounts of clay, silt, and gravel were encountered in some borings.

Auger refusal was encountered at depths ranging from about 3 to 5.5 below existing ground surface in some borings.

The subgrade soils classified as A-4, A-6, and A-7-6 in accordance with the AASHTO Soil

Classification system. Groundwater was not encountered in any of the borings at the time of drilling. Based upon the AASHTO soil classifications and R-value test results, the majority of the subgrade soils are considered to be poor quality for roadway/pavement support.

Based upon the limited thickness of existing pavement materials, reduce export and import of subgrade and pavement materials, and to maintain proposed grades near existing grades, it is our understanding that that the proposed new pavement section will consist of a new hot asphalt concrete pavement (HACP) surface over the existing pavement materials and subgrade following full depth reclamation (FDR) operations using cement stabilization. In addition, a crushed aggregate base (CAB) layer will be incorporated below the HACP surface layer within the recommended Heron Lake pavement sections to compensate for the thinner pavement section and higher traffic volumes.

During the FDR process, any unstable existing pavement/subgrade areas will require stabilization prior to the placement of new pavement materials. These locations will likely be associated with areas of existing drainage culverts/structures, thin pavement section, poor quality subgrade soils, structural pavement distress, high severity transverse and longitudinal cracking, and/or areas exhibiting low density and elevated moisture contents within the underlying subgrade.

At the existing drainage culverts/structures located at approximate Station Nos. 145+40 and

152+20, it is our opinion that the existing pavement distress is likely associated with backfill settlement and/or erosion/undermining of the bearing support soils. Therefore, we recommend that an assessment be made of the subgrade and backfill materials during construction to determine the appropriate corrective action. Existing backfill may require removal and replacement/recompaction.

The recommended pavement sections outlined in this report are considered the minimum sections based upon the traffic information provided (including large trucks, RVs, and trailers), estimated growth rate, poor quality subgrade soils, meeting a minimum 20-year design life, accounting for climatic variations, providing a durable pavement, and reducing future maintenance.

Geotechnical engineering recommendations for pavements and other earth connected phases of the project are outlined below. The recommendations contained in this report are based upon the results of field and laboratory testing (which are presented in Appendices A and B), engineering analyses, and our current understanding of the proposed project.

4.2 Earthwork

The following presents recommendations for site preparation, excavation, subgrade preparation and placement of engineered fills on the project. The recommendations presented for design and construction of earth supported elements including pavements are contingent upon following the recommendations outlined in this section. The Standard Specifications for Construction of Roads and Bridges on Federal Highway Projects FP-14”, referred hereafter as the Specifications, should be used for the project.

Earthwork, site preparation, and excavations should be performed in accordance with Section

200, “Earthwork” of the Specifications.

Earthwork on the project should be observed and evaluated by Terracon. The evaluation of earthwork should include observation and testing of structural fill, backfill, subgrade preparation, and other geotechnical conditions exposed during the construction of the project.

4.2.1 Site Preparation

Site preparation should be performed in accordance with Section 201, “Clearing and Grubbing” , Section 203 “Removal of structures and Obstructions”, Section 209 “Structure Excavation and

Backfill”, and Section 211, “Obliterating Old Road” (where applicable) of the Specifications.

Strip and remove existing pavement (where applicable), vegetation, debris, and other deleterious materials from proposed new pavement reconstruction or rehabilitation areas. Exposed surfaces should be free of mounds and depressions which could prevent uniform compaction.

FDR should be performed in accordance with Section 305, “Full Depth Reclamation with Cement” of the Specifications.

Stripped materials consisting of vegetation and organic materials (where encountered) should be wasted from the site, or used to revegetate exposed slopes after completion of grading operations

(if required). If it is necessary to dispose of organic materials on-site, they should be placed in non-structural areas, and in fill sections not exceeding five (5) feet in height.

Evidence indicating the potential presence of underground utilities adjacent to and within the project alignment was observed during the field operations. If abandoned utilities or loose fills or other underground facilities are encountered, such features should be removed and the excavation thoroughly cleaned prior to backfill placement and/or construction.

4.2.2 Excavation and Embankment

Excavation and embankment construction (if applicable) should be performed in accordance with

Section 204, “Excavation and Embankment” of the Specifications.

It is anticipated that shallow excavations for the proposed construction can be accomplished with conventional earthmoving equipment. However, auger refusal was encountered at depths ranging from about 3 to 5.5 below existing ground surface in some borings. Therefore, excavation depths approaching about 3 feet or more may require heavy-duty or specialized equipment.

Based upon the subsurface conditions determined from the geotechnical exploration, excavations into the on-site soils may encounter caving soils.

Based on the results from the soil borings, we do not anticipate groundwater control measures will be necessary in excavations up to about 6.5 feet below existing site grades. However, localized groundwater may be encountered during precipitation events.

At the existing drainage culverts/structures located at approximate Station Nos. 145+40 and

152+20, it is our opinion that the existing pavement distress is likely associated with backfill settlement and/or erosion/undermining of the bearing support soils. Therefore, we recommend that an assessment be made of the subgrade and backfill materials during construction to determine the appropriate corrective action. Existing backfill may require removal and replacement/recompaction.

The individual contractor(s) is responsible for designing and constructing stable, temporary excavations as required to maintain stability of both the excavation sides and bottom.

Excavations should be sloped or shored in the interest of safety following local and federal regulations, including current OSHA excavation and trench safety standards.

4.2.3 Subgrade Preparation

If stabilization of the subgrade is required in some areas, subgrade preparation should be conducted in accordance with Section 212 “Linear Grading” of the Specifications.

We anticipate that the subgrade soils will be relatively stable. However, medium stiff soils and elevated moisture contents were encountered within the subgrade along portions of the project alignments. The stability of the subgrade may also be affected by precipitation, repetitive construction traffic or other factors. If unstable conditions develop, workability may be improved by scarifying and drying. Overexcavation of wet zones and replacement with granular materials may be necessary. Lightweight excavation equipment may be required to reduce subgrade pumping.

Based upon the AASHTO soil classifications and R-value test results, the majority of the subgrade soils are considered to be poor quality for roadway/pavement support. Subgrade stabilization (if required) should be performed in accordance with Section 207 “Earthwork Geosynthetics” and/or

Section 213 “Subgrade Stabilization” of the Specifications.

4.2.4 Materials and Placement

All fill materials should be inorganic soils free of vegetation, debris, and fragments larger than six

(6) inches in size. Pea gravel or other similar non-cementitious, poorly graded materials should not be used as fill or backfill without the prior approval of the geotechnical engineer.

Clean on-site soils or approved imported materials may be used as fill material for the following:

◼ general site grading

◼ utility trench backfill

◼ new pavement areas

Imported soils for use as fill material should conform to low volume change materials as indicated in the following specifications:

Percent Finer by Weight

Gradation (ASTM C 136)

6"

3” .................................................................................................... 70-100

No. 4 Sieve ..................................................................................... 50-100

No. 200 Sieve .............................................................................. 70 (max)

◼ Liquid Limit ....................................................................... 35 (max)

◼ Plasticity Index ................................................................. 15 (max)

◼ Minimum R-value

Engineered fill should be placed and compacted in horizontal lifts, using equipment and procedures that will produce recommended moisture contents and densities throughout the lift.

Fill lifts should not exceed eight (8) inches loose thickness.

4.2.5 Compaction Requirements

Recommended compaction and moisture content criteria for engineered fill or backfill materials per Sections 204, 209, 212, 301, and 305 of the Specifications are as follows:

Material Type and Location

Per the Modified Proctor Test (AASHTO T99/ASTM D

698)

Minimum

Compaction

Requirement (%)

Range of Moisture Contents for

Compaction

Minimum Maximum

Roadway Embankment 95 -2% +2%

Beneath Pavements (top 6 inches) 95 -2% +2%

Minor Structure or Utility Trench Backfill 95 -2% +2%

Base Course (where used):

Material Type and Location

Per the Modified Proctor Test (AASHTO T180/ASTM D

1557)

Minimum

Compaction

Requirement (%)

Range of Moisture Contents for

Compaction

Minimum Maximum

Untreated Aggregate Courses/Base Course 95 -3% +3%

4.2.6 Grading and Drainage

Positive drainage should be provided during construction and maintained throughout the life of the project. Infiltration of water into utility trenches, excavations, or adjacent to pavements should be prevented during construction. Water should not be allowed to pond adjacent to pavements.

Backfill in utility trenches (if applicable) should be well compacted and free of any construction debris to reduce the possibility of moisture infiltration.

4.2.7 Corrosion Potential

Based upon our experience with projects in the area and similar subsurface soil conditions, it is our opinion that the concrete corrosion potential is considered to be low to moderate and the metal corrosion potential is considered to be moderate to high.

Therefore, it is our opinion that ASTM Type I-II or II Portland cement should be specified for all concrete on and below grade. Foundation concrete should be designed for negligible sulfate exposure in accordance with the provisions of the ACI Design Manual, Section 318, Chapter 4.

Metal conduits or drainage structures should be designed for a high corrosion resistance.

4.3 Pavements

Based upon the limited thickness of existing pavement materials, reduce export and import of subgrade and pavement materials, and to maintain proposed grades near existing grades, it is our understanding that that the proposed new pavement section will consist of a new hot asphalt concrete pavement (HACP) surface over the existing pavement materials and subgrade following full depth reclamation (FDR) operations using cement stabilization. In addition, a crushed aggregate base (CAB) layer will be incorporated below the HACP surface layer within the recommended Heron Lake pavement sections to compensate for the thinner pavement section and higher traffic volumes.

During the FDR process, any unstable existing pavement/subgrade areas will require stabilization prior to the placement of new pavement materials. These locations will likely be associated with areas of existing thin pavement section, poor quality subgrade soils, structural pavement distress, high severity transverse and longitudinal cracking, and/or areas exhibiting low density and elevated moisture contents within the underlying subgrade.

The recommended pavement sections outlined below are considered the minimum sections based upon the traffic information provided (including large trucks, RVs, and trailers), estimated growth rate, poor quality subgrade soils, meeting a minimum 20-year design life, accounting for climatic variations, providing a durable pavement, and reducing future maintenance.

4.3.1 Design Recommendations

Design of the pavement thickness has been performed based upon AASHTO criteria and design methodology. The traffic used in the pavement design was obtained from the Bureau of

Reclamation (Albuquerque Office), Federal Highway Administration (FHWA), Central Federal

Lands Highway Division (CFLHD), and DJ&A and included the following:

◼ Heron Lake annual visitors = 118,000

◼ El Vado annual visitors = 40,000

◼ Heron Lake annual vehicles = 47,200 (using factor of 2.5)

◼ El Vado annual vehicles = 16,000 (using factor of 2.5)

◼ Parking areas traffic = 10% of annual vehicles

◼ Class 5 vehicles = 25% (RVs, trailers, motorhomes, small buses, delivery trucks)

◼ Class 8 vehicles = 1% (semi-tractor trailer, large delivery trucks, trash trucks, large buses, large emergency response vehicles)

◼ 2% annual growth rate

◼ 20-year design

Using the estimated traffic data above, the 18-Kip Equivalent Single Axle Loads (ESALs) were calculated as follows:

Location Traffic Area 20-Year 18-KIP Equivalent Single

Axle Load (ESAL)

Heron Lake

Visitor Center Parking 1 8,245

Ridge Rock Access Road 82,453

Ridge Rock Parking 1 8,245

Narrows Boat Ramp Access

Road 82,453

Narrows Boat Ramp Parking 1 8,245

El Vado State Park Road 5001 28,124

Parking 1 2,812

1. ESAL based upon 10% of annual vehicles

A detailed summary of the ESAL calculations are included in Appendix C.

Design of pavements was based upon AASHTO design methodology utilizing a design R-value of 8 and FP-14 specifications. The following parameters were used in the design of the flexible pavement:

◼ Initial serviceability index (Pi) of 4.2

◼ Terminal serviceability index (Pt) of 2.0

◼ Reliability of 65%

◼ Standard deviation of 0.45

◼ Layer structural coefficients of 0.44 for new hot asphalt concrete pavement (HACP),

0.14 for crushed aggregate base (CAB), and 0.22 for full depth reclamation (FDR) with cement.

Based upon AASHTO design methodology, the recommended new pavement section thickness is outlined below:

Location Pavement Area Recommended Pavement Section (in.)

HACP 1 CAB 1 FDR 2,3

Heron Lake

Visitor Center Parking 4 3 4 N/A

Ridge Rock Access Road 3 2 4

Ridge Rock Parking 3 2 4

Narrows Boat Ramp

Access Road 3 2 4

Narrows Boat Ramp

Parking 3 2 4

El Vado State Park Road 5001 3 N/A 4

Parking 3 N/A 4

5. New pavement surface layers

6. Assumes a minimum of 4 inches of FDR using cement stabilization.

7. Preliminary estimated minimum cement content of 10%. Actual minimum cement content to be determined by mix design per the Specifications

8. Requires reconstruction to maintain existing grade constraints

It should be noted that during the FDR process, any unstable existing pavement/subgrade areas will require stabilization prior to the placement of new pavement materials. These locations will likely be associated with areas of existing structural pavement distress, high severity transverse and longitudinal cracking, and/or areas exhibiting low density and elevated moisture contents within the underlying subgrade.

The AASHTO pavement design thickness spreadsheets are included in Appendix C.

4.3.2 Materials Specifications

The recommended pavement sections should consist of asphalt concrete, meeting the gradation and properties of Type I or II per Section 401, “Asphalt Concrete Pavement By Gyratory Mix

Design Method”, Section 402 “Asphalt Concrete”, Section 702 “Asphalt Material”, and Section

703 “Aggregate” of the Specifications. The HMAC mix design should be submitted prior to construction to verify its adequacy and should be placed and compacted in accordance with procedures outlined in the Specifications.

FDR should be performed in accordance with Section 305, “Full Depth Reclamation with Cement” of the Specifications. The FDR mix design should meet a minimum 7-day compressive strength of 200 pounds per square inch (psi) in accordance with procedures outlined in the Specifications.

The asphalt concrete should be compacted to a minimum density of at least 91% of the theoretical maximum density as determined by AASHTO T 209.

The base course should consist of a blend of sand and gravel, which meets strict specifications for quality and gradation. Use of materials meeting Type I of Section 301, “Untreated Aggregate

Courses”. Base course material should be tested to determine compliance with these specifications prior to importation to the site. Aggregate base course should be compacted to a minimum 95% of maximum dry density and within 2 percent of optimum moisture content as determined by AASHTO T180.

4.3.3 Pavement Maintenance

Service life of the pavement is based on periodic pavement maintenance, adequate drainage, and traffic consistent with the stated assumptions in this report. Preventive maintenance should be planned and provided for through an on-going pavement management program. Preventive maintenance activities are intended to slow the rate of pavement deterioration, and to preserve the pavement investment. Preventive maintenance consists of both localized maintenance (e.g.

crack and joint sealing and patching) and global maintenance (e.g. surface sealing). Preventive maintenance is usually the first priority when implementing a planned pavement maintenance program and provides the highest return on investment for pavements. Prior to implementing any maintenance, additional engineering observation is recommended to determine the type and extent of preventive maintenance.

Long term pavement performance depends on several factors, including maintaining subgrade moisture levels and providing for preventive maintenance. The following recommendations should be considered the minimum:

◼ Site grading at a minimum 2% grade away from the pavements;

◼ The subgrade and the pavement surface have a minimum ¾ inch per foot slope to promote proper surface drainage.

◼ Consider appropriate edge drainage and pavement under drain systems, ◼ Install joint sealant and seal cracks immediately

5.0 GENERAL COMMENTS

Terracon should be retained to review the final design plans and specifications so comments can be made regarding interpretation and implementation of our geotechnical recommendations in the design and specifications. Terracon also should be retained to provide observation and testing services during grading, excavation, pavement construction and other earth-related construction phases of the project.

The analysis and recommendations presented in this report are based upon the data obtained from the borings performed at the indicated locations and from other information discussed in this report. This report does not reflect variations that may occur between borings, across the site, or due to the modifying effects of construction or weather. The nature and extent of such variations may not become evident until during or after construction. If variations appear, we should be immediately notified so that further evaluation and supplemental recommendations can be provided.

The scope of services for this project does not include either specifically or by implication any environmental or biological (e.g., mold, fungi, bacteria) assessment of the site or identification or prevention of pollutants, hazardous materials or conditions. If the owner is concerned about the potential for such contamination or pollution, other studies should be undertaken.

This report has been prepared for the exclusive use of our client for specific application to the project discussed and has been prepared in accordance with generally accepted geotechnical engineering practices. No warranties, express or implied, are intended or made. Site safety, excavation support, and dewatering requirements are the responsibility of others. In the event that changes in the nature, design, or location of the project as outlined in this report are planned, the conclusions and recommendations contained in this report shall not be considered valid unless Terracon reviews the changes and either verifies or modifies the conclusions of this report in writing.

APPENDIX A

FIELD EXPLORATION

Proposal for Geotechnical Engineering Services

Roadway and Parking Lot Rehabilitation | Tierra Amarilla, NM

April 4, 2024 | Terracon Project No. 66225032

Note to Preparer: This is a large table with outside borders. Just click inside the table above this text box, then paste your GIS Toolbox image.

When paragraph markers are turned on you may notice a line of hidden text above and outside the table – please leave that alone. Limit editing to inside the table.

The line at the bottom about the general location is a separate table line. You can edit it as desired, but try to keep to a single line of text to avoid reformatting the page.

Exploration Plan – El Vado Main Parking Lot and Boat Ramp

DIAGRAM IS FOR GENERAL LOCATION ONLY, AND IS NOT INTENDED FOR CONSTRUCTION PURPOSES MAP PROVIDED BY MICROSOFT BING MAPS

Exploration Plan – El Vado Phase I State Park Road 5001

DIAGRAM IS FOR GENERAL LOCATION ONLY, AND IS NOT INTENDED FOR CONSTRUCTION PURPOSES MAP PROVIDED BY MICROSOFT BING MAPS

Facilities | Environmental | Geotechnical | Materials

Exploration Plan – Heron Lake Ridge Rock Access Road and Parking

DIAGRAM IS FOR GENERAL LOCATION ONLY, AND IS NOT INTENDED FOR CONSTRUCTION PURPOSES MAP PROVIDED BY MICROSOFT BING MAPS

Exploration Plan – Heron Lake Visitors Center

DIAGRAM IS FOR GENERAL LOCATION ONLY, AND IS NOT INTENDED FOR CONSTRUCTION PURPOSES MAP PROVIDED BY MICROSOFT BING MAPS

Exploration Plan – Heron Lake Narrows Boat Ramp Access Road and Parking Lot

DIAGRAM IS FOR GENERAL LOCATION ONLY, AND IS NOT INTENDED FOR CONSTRUCTION PURPOSES MAP PROVIDED BY MICROSOFT BING MAPS

Field Exploration Description

A total of 25 test borings were advanced along the existing roadways and parking areas between the period of November 28 to December 1, 2023. The location of borings are shown on the attached Site Location Map and Exploration Plan. The location and depth of borings are summarized in the table below:

Boring Designation No. Location Approximate Depth (feet)

B-01A through B-01C

B-02B

B-03A

B-04A

Heron Lake 3 to 6.5 1

B-01D and B-01E

B-02C

B-03B

B-04B

B-05 through B-18

El Vado Reservoir 4 to 6.5 2

1. Auger refusal encountered in Boring Nos. B-01C and B-02B at depths of approximately 3 to 5 feet below existing ground surface

2. Auger refusal encountered in Boring Nos. B-04B, B-06, B-07, B-09, and B-10 at depths of approximately 4 to

5.5 feet below existing ground surface

The test borings along the existing roadway alignment and parking areas were advanced with a truck-mounted CME-75 drill rig utilizing 7-½ inch outside diameter hollow-stem augers.

The borings were located in the field by using existing site features and the Google Earth .kmz file provided by DJ&A. The latitude, longitude, and approximate elevation were obtained at each boring location using a hand-held GPS unit. The accuracy of boring locations and elevations should only be assumed to the level implied by the method used.

Lithologic logs of the borings were recorded by the Terracon representative during the drilling and hand auger operations. The existing pavement materials along the existing roadway were measured and documented at each boring location. At selected intervals, samples of the subsurface materials were taken by driving split-spoon or ring-barrel samplers. In addition, bulk samples were obtained at selected intervals within some borings.

Within the borings along the existing roadway alignment, penetration resistance measurements were obtained by driving the split-spoon and ring-barrel samplers into the subsurface materials with a 140-pound automatic hammer falling 30 inches. The penetration resistance value is a useful index in estimating the consistency or relative density of materials encountered.

A CME automatic SPT hammer was used to advance the split-barrel sampler in the borings performed along the existing roadway. The effect of the automatic hammer's efficiency has been considered in the interpretation and analysis of the subsurface information for this report.

Groundwater conditions were evaluated in the borings at the time of site exploration. Due to safety considerations, the existing borings were backfilled with native soils and patched upon completion of drilling operations.

7296.83

7290.5

ASPHALT - 2"

SANDY LEAN CLAY (CL), trace gravel, dark brown, medium stiff to very stiff, AASHTO: A-6

Boring Terminated at 6.5 Feet

Boring Log No. B-01A

W at er L ev el

O bs er va tio ns

D ep th

Ft

Facilities | Environmental | Geotechnical | Materials

G ra p h ic

L o g

6514.3

24.8

25.4 97

28-16-12

0.2

6.5

6-8-7 N=15

3-3-3 N=6

8-12

El Vado Lake and Heron Lake, NM | Tierra Amarilla, NM

Terracon Project No. 66225032 Albuquerque, NM

6805 Academy Pkwy West NE

Drill Rig

CME 75

Hammer Type Automatic

Driller

EDI

Logged by

ED

Boring Started 11-28-2023

Boring Completed 11-28-2023

Abandonment Method Boring backfilled with Auger Cuttings Surface capped with asphalt

Advancement Method 8" Hollow Stem Auger

Notes

Water Level Observations Groundwater not encountered

See Exploration and Testing Procedures for a description of field and laboratory procedures used and additional data (If any).

See Supporting Information for explanation of symbols and abbreviations.

Elevation Reference: Elevations measured in the field

Roadway and Parking Lot Rehabilitation

S am pl e

T yp e

Pe rc en t

Fi n es

W at er C o n te n t

D ry

U n it

W ei g h t

(p cf

Elevation: 7297 (Ft.) +/-

Atterberg Limits

LL-PL-PI

See Exploration PlanLocation:

Latitude: 36.6967° Longitude: -106.6530°

Station: Heron Lake

Depth (Ft.)

S W

E

LL

Fi el d T es t

R es u lt s

ASPHALT- 2"

FAT CLAY WITH SAND (CH), trace gravel, dark brown, stiff to hard, AASHTO: A-7-6

Boring Terminated at 6.5 Feet

7247.83

7241.5

Boring Log No. B-01B

W at er L ev el

O bs er va tio ns

D ep th

Ft

Facilities | Environmental | Geotechnical | Materials

G ra p h ic

L o g

0.2

6.5

11-9-6 N=15

10-23

14-18-23 N=41

13.9

13.3

12.1

91 50-21-29

El Vado Lake and Heron Lake, NM | Tierra Amarilla, NM

Terracon Project No. 66225032 Albuquerque, NM

6805 Academy Pkwy West NE

Drill Rig

CME 75

Hammer Type Automatic

Driller

EDI

Logged by

ED

Boring Started 11-28-2023

Boring Completed 11-28-2023

Abandonment Method Boring backfilled with Auger Cuttings Surface capped with asphalt

Advancement Method 8" Hollow Stem Auger

Notes

Water Level Observations Groundwater not encountered

See Exploration and Testing Procedures for a description of field and laboratory procedures used and additional data (If any).

See Supporting Information for explanation of symbols and abbreviations.

Elevation Reference: Elevations measured in the field

Roadway and Parking Lot Rehabilitation

S am pl e

T yp e

Pe rc en t

Fi n es

Depth (Ft.)

S W

E

LL

Fi el d T es t

R es u lt s

W at er C o n te n t

D ry

U n it

W ei g h t

(p cf

Elevation: 7248 (Ft.) +/-

Atterberg Limits

LL-PL-PI

See Exploration PlanLocation:

Latitude: 36.6932° Longitude: -106.6574°

Station: Heron Lake

7296.83

7291.75

ASPHALT- 2"

SILTY SAND WITH GRAVEL (SM), trace gravel, dark brown, dense to very dense, AASHTO: A-4

Auger Refusal at 5.25 Feet

Boring Log No. B-01C

W at er L ev el

O bs er va tio ns

D ep th

Ft

Facilities | Environmental | Geotechnical | Materials

G ra p h ic

L o g

4013.4

6.2

NP11-12-18

N=30

23-50/3"

50/3"

0.2

5.3

El Vado Lake and Heron Lake, NM | Tierra Amarilla, NM

Terracon Project No. 66225032 Albuquerque, NM

6805 Academy Pkwy West NE

Drill Rig

CME 75

Hammer Type Automatic

Driller

EDI

Logged by

ED

Boring Started 11-28-2023

Boring Completed 11-28-2023

Abandonment Method Boring backfilled with Auger Cuttings Surface capped with asphalt

Advancement Method 8" Hollow Stem Auger

Notes

Water Level Observations Groundwater not encountered

See Exploration and Testing Procedures for a description of field and laboratory procedures used and additional data (If any).

See Supporting Information for explanation of symbols and abbreviations.

Elevation Reference: Elevations measured in the field

Roadway and Parking Lot Rehabilitation

S am pl e

T yp e

Pe rc en t

Fi n es

W at er C o n te n t

D ry

U n it

W ei g h t

(p cf

Elevation: 7297 (Ft.) +/-

Atterberg Limits

LL-PL-PI

See Exploration PlanLocation:

Latitude: 36.6666° Longitude: -106.7077°

Station: Heron Lake

Depth (Ft.)

S W

E

LL

Fi el d T es t

R es u

6914.83

6908.5

GRAVEL SURFACING - 2"

LEAN CLAY (CL), trace gravel, dark brown, stiff to very stiff, AASHTO: A-7-6

Boring Terminated at 6.5 Feet

Boring Log No. B-01D

W at er L ev el

O bs er va tio ns

D ep th

Ft

Facilities | Environmental | Geotechnical | Materials

G ra p h ic

L o g

9018.4

18.2

17.3

44-19-25

0.2

6.5

6-4-5 N=9

12-10

7-7-7 N=14

El Vado Lake and Heron Lake, NM | Tierra Amarilla, NM

Terracon Project No. 66225032 Albuquerque, NM

6805 Academy Pkwy West NE

Drill Rig

CME 75

Hammer Type Automatic

Driller

EDI

Logged by

ED

Boring Started 11-30-2023

Boring Completed 11-30-2023

Abandonment Method Boring backfilled with auger cuttings upon completion.

Advancement Method 8" Hollow Stem Auger

Notes

Water Level Observations Groundwater not encountered

See Exploration and Testing Procedures for a description of field and laboratory procedures used and additional data (If any).

See Supporting Information for explanation of symbols and abbreviations.

Elevation Reference: Elevations measured in the field

Roadway and Parking Lot Rehabilitation

S am pl e

T yp e

Pe rc en t

Fi n es

W at er C o n te n t

D ry

U n it

W ei g h t

(p cf

Elevation: 6915 (Ft.) +/-

Atterberg Limits

LL-PL-PI

See Exploration PlanLocation:

Latitude: 36.6112° Longitude: -106.7395°

Station: El Vado Lake

Depth (Ft.)

S W

E

LL

Fi el d T es t

R es u

6926.83

6920.5

GRAVEL SURFACING - 2"

GRAVELLY LEAN CLAY WITH SAND (CL), dark brown, stiff to very stiff, AASHTO: A-7-6

Boring Terminated at 6.5 Feet

Boring Log No. B-01E

W at er L ev el

O bs er va tio ns

D ep th

Ft

Facilities | Environmental | Geotechnical | Materials

G ra p h ic

L o g

15.1

11.5

13.5

71 45-18-27

0.2

6.5

12-7-4 N=11

12-14

8-7-7 N=14

El Vado Lake and Heron Lake, NM | Tierra Amarilla, NM

Terracon Project No. 66225032 Albuquerque, NM

6805 Academy Pkwy West NE

Drill Rig

CME 75

Hammer Type Automatic

Driller

EDI

Logged by

ED

Boring Started 12-01-2023

Boring Completed 12-01-2023

Abandonment Method Boring backfilled with auger cuttings upon completion.

Advancement Method 8" Hollow Stem Auger

Notes

Water Level Observations Groundwater not encountered

See Exploration and Testing Procedures for a description of field and laboratory procedures used and additional data (If any).

See Supporting Information for explanation of symbols and abbreviations.

Elevation Reference: Elevations measured in the field

Roadway and Parking Lot Rehabilitation

S am pl e

T yp e

Pe rc en t

Fi n es

W at er C o n te n t

D ry

U n it

W ei g h t

(p cf

Elevation: 6927 (Ft.) +/-

Atterberg Limits

LL-PL-PI

See Exploration PlanLocation:

Latitude: 36.6112° Longitude: -106.7398°

Station: El Vado Lake

Depth (Ft.)

S W

E

LL

Fi el d T es t

R es u

7213.83

ASPHALT-2"

SANDY LEAN CLAY (CL), dark brown, stiff to hard, AASHTO: A-6

Auger Refusal at 3 Feet

Boring Log No. B-02B

W at er L ev el

O bs er va tio ns

D ep th

Ft

Facilities | Environmental | Geotechnical | Materials

G ra p h ic

L o g

14.3

9.4 27-15-12

0.2

3.0

5-4-10 N=14

50/2"

El Vado Lake and Heron Lake, NM | Tierra Amarilla, NM

Terracon Project No. 66225032 Albuquerque, NM

6805 Academy Pkwy West NE

Drill Rig

CME 75

Hammer Type Automatic

Driller

EDI

Logged by

ED

Boring Started 11-28-2023

Boring Completed 11-28-2023

Abandonment Method Boring backfilled with Auger Cuttings Surface capped with asphalt

Advancement Method 8" Hollow Stem Auger

Notes

Water Level Observations Groundwater not encountered

See Exploration and Testing Procedures for a description of field and laboratory procedures used and additional data (If any).

See Supporting Information for explanation of symbols and abbreviations.

Elevation Reference: Elevations measured in the field

Roadway and Parking Lot Rehabilitation

S am pl e

T yp e

Pe rc en t

Fi n es

W at er C o n te n t

D ry

U n it

W ei g h t

(p cf

Elevation: 7214 (Ft.) +/-

Atterberg Limits

LL-PL-PI

See Exploration PlanLocation:

Latitude: 36.6671° Longitude: -106.7093°

Station: Heron Lake

Depth (Ft.)

S W

E

LL

Fi el d T es t

R es u

6942.75

ASPHALT- 3"

LEAN CLAY (CL), dark brown, stiff to very stiff, AASHTO: A-7-6

Boring Terminated at 6 Feet

Boring Log No. B-02C

W at er L ev el

O bs er va tio ns

D ep th

Ft

Facilities | Environmental | Geotechnical | Materials

G ra p h ic

L o g

21.0

19.6

18.3 100

7-6-3 N=9

5-7-12 N=19

16-10 49-20-29

0.3

6.0

El Vado Lake and Heron Lake, NM | Tierra Amarilla, NM

Terracon Project No. 66225032 Albuquerque, NM

6805 Academy Pkwy West NE

Drill Rig

CME 75

Hammer Type Automatic

Driller

EDI

Logged by

ED

Boring Started 11-30-2023

Boring Completed 11-30-2023

Abandonment Method Boring backfilled with Auger Cuttings Surface capped with asphalt

Advancement Method 8" Hollow Stem Auger

Notes

Water Level Observations Groundwater not encountered

See Exploration and Testing Procedures for a description of field and laboratory procedures used and additional data (If any).

See Supporting Information for explanation of symbols and abbreviations.

Elevation Reference: Elevations measured in the field

Roadway and Parking Lot Rehabilitation

S am pl e

T yp e

Pe rc en t

Fi n es

W at er C o n te n t

D ry

U n it

W ei g h t

(p cf

Elevation: 6943 (Ft.) +/-

Atterberg Limits

Fi el d T es t

R es u lt s

LL-PL-PI

See Exploration PlanLocation:

Latitude: 36.6145° Longitude: -106.7380°

Station: El Vado Lake

Depth (Ft.)

S W

E

LL

7204.83

ASPHALT-2"

FAT CLAY WITH SAND (CL), dark brown, medium stiff to very stiff, AASHTO: A-7-6

Boring Terminated at 6 Feet

Boring Log No. B-03A

W at er L ev el

O bs er va tio ns

D ep th

Ft

Facilities | Environmental | Geotechnical | Materials

G ra p h ic

L o g

7418.7

22.3

23.9 99

50-20-30

0.2

6.0

4-4-3 N=7

4-6-7 N=13

6-14

El Vado Lake and Heron Lake, NM | Tierra Amarilla, NM

Terracon Project No. 66225032 Albuquerque, NM

6805 Academy…