Tab_14__PVT_Memo_adv (2).pdf

GEOTECHNICAL AND PAVEMENT ENGINEERING REPORT

FOXVILLE-DEERFIELD ROAD AND PARK CENTRAL ROAD

Catoctin Mountain National Park, Maryland EFL Project: CATO 10(5) 11(2) ETC

Schnabel Reference 21C14015.00 April 5, 2022

Prepared for:

April 5, 2022

Mr. Timothy J. Ramey, PE

WSP USA

13530 Dulles Technology Drive, Suite 300 Herndon, Virginia 20171

Subject: Geotechnical and Pavement Engineering Report, Foxville-Deerfield Road and Park Central Road, CATO 10(5) 11(2) ETC, Catoctin Mountain National Park, Maryland (Schnabel Reference 21C14015)

Dear Mr. Ramey:

SCHNABEL ENGINEERING, LLC (Schnabel) is pleased to submit our final geotechnical and pavement engineering report for this project. This final report has been revised to address review comments.

This study was performed in accordance with the scope of services identified in our revised proposal dated March 15, 2021, which is based on the requirements of the Section C Statement of Work (SOW) for the CATO 10(5) 11(2) – Preparation of The Plans, Specification, and Estimate Project Management and Technical Assistance Project. In addition, we considered our correspondence with Eastern Federal Lands (EFL) to optimize our subsurface exploration program based on the data provided with the RFP including the Road Inventory and Condition Assessment of Paved Routes Report (Cycle 6 Report) and the Design Scoping Report dated August 2020.

We appreciate the opportunity to be of service for this project. Please call us if you have any questions regarding this report.

Sincerely, SCHNABEL ENGINEERING, LLC

Ken Derrenbacher, PE Federico Ayala, EIT Principal Senior Staff Engineer Professional Certification. I hereby certify that these documents were prepared or approved by me, and that I am a duly licensed professional engineer under the laws of the State of Maryland. License No. 16495, Expiration Date: 5/18/2023

Christopher Clarke, PE Senior Associate Professional Certification. I hereby certify that these documents were prepared or approved by me, and that I am a duly licensed professional engineer under the laws of the state of Maryland. License No. 45089, Expiration Date: 2/24/2024 \\BALT-FS\PROJECTS\2021 PROJECTS\BALTIMORE\21C14015.00 EFL CATOCTIN PAVEMENTS\SE PRODUCTS\REPORTS\DRAFT\GER 21C14015.DOCX

WSP USA

Foxville-Deerfield Road and Park Central Road

April 5, 2022 Page i Schnabel Engineering, LLC Project 21C14015 ©2022 All Rights Reserved

GEOTECHNICAL AND PAVEMENT ENGINEERING REPORT

FOXVILLE-DEERFIELD ROAD AND PARK CENTRAL ROAD

CATOCTIN MOUNTAIN NATIONAL PARK, MARYLAND

TABLE OF CONTENTS

1.0 EXECUTIVE SUMMARY

2.0 SCOPE OF SERVICES

3.0 DESCRIPTION OF SITE AND PROPOSED CONSTRUCTION

3.1 Site Description

3.2 Proposed Construction

3.3 Traffic Data

3.4 Regional Geology

4.0 SITE EXPLORATION PROGRAM

4.1 Test Borings and Pavement Cores

4.2 Pavement Condition Assessment

4.3 Ground Penetrating Radar

5.0 SOIL LABORATORY TESTING

5.1 Index Testing

5.2 Compaction and CBR Testing

5.3 Corrosivity Testing

6.0 SITE GEOLOGY, PAVEMENT, AND SUBSURFACE CONDITIONS

6.1 Site Geology

6.2 Generalized Subsurface Stratigraphy

6.3 Groundwater

6.4 Moisture Density Relationship and CBR Testing

7.0 PAVEMENT ANALYSES AND RECOMMENDATIONS

7.1 Pavement Condition Assessment

7.2 Pavement Recommendations

8.0 SITE GRADING AND EARTHWORK

8.1 Compacted Fill Subgrades

8.2 Compacted Fill

9.0 CONSTRUCTION CONSIDERATIONS

9.1 Site Grading and Earthwork

9.2 General Specification Recommendations

10.0 LIMITATIONS

April 5, 2022 Page ii Schnabel Engineering, LLC

LIST OF FIGURES

Figure 1: Site Vicinity Map Figure 2: Geologic Map Figures 3A to 3H: Subsurface Exploration Plans

LIST OF TABLES

Table 1: Pavement Design Parameters Table 2: Foxville-Deerfield Road from MP 0 (STA 10+84) to MP 1.08 (STA 67+60) Table 3: Foxville-Deerfield Road from MP 1.08 (STA 67+60) to MP 1.86 (STA 109+47) Table 4: Park Central Road from MP 0 (STA 394+00) to MP 0.2 (STA 384+00) Table 5: Park Central Road from MP 0.2 (STA 384+00) to MP 2.52 (STA 260+50), Wolf Rock Parking, and Park Central Picnic Parking Table 6: Park Central Road from MP 2.52 (STA 260+50) to MP 3.66 (STA 200+00) and Camp 3 Turnaround

APPENDICES

Appendix A: Subsurface Exploration Data Appendix B: Soil Laboratory Test Data Appendix C: Pavement Investigation Data, PCR Maps, and Patching Quantities Appendix D: Pavement Distress Photo Log Appendix E: Pavement Condition and Pavement Thickness Evaluation Summary Report, Advanced Infrastructure Design, Inc.

Appendix F: Calculations

April 5, 2022 Page 1 Schnabel Engineering, LLC

1.0 EXECUTIVE SUMMARY

This report presents the results of our pavement condition assessment, subsurface exploration, laboratory testing, and geotechnical and pavement engineering analysis and recommendations for the proposed pavement rehabilitation and reconstruction of Foxville-Deerfield Road and Park Central Road.

We provide this executive summary solely for purposes of overview. Any party that relies on this report must read the full report. This executive summary omits several details, any one of which could be very important to the proper application of the report.

• Our subsurface exploration and pavement cores encountered asphalt pavement thicknesses ranging from 4.5 to 8.5 inches with an average of 6.5 inches for Park Central Road and 7.5 to 12 inches with an average of 9.5 inches for Foxville Deerfield Road.

• Only two of the 11 borings performed within Foxville-Deerfield Road encountered aggregate base below the asphalt pavement. Seven of the 17 borings drilled on Park Central Road had aggregate base below the asphalt. It appears that the asphalt pavement between Route 77 and Camp 3 is supported directly on the soil subgrade.

• Below the asphalt pavement, we encountered the existing fill soils (Stratum A), which extended to depths ranging from 1.5 to 5 ft below the ground surface, in 12 of the 32 test borings drilled.

Underlying the existing fills or the pavement materials, we encountered the residual soils (Stratum B) in 25 of the 32 test borings to depths ranging from 2.2 to 10 ft. We also encountered the Disintegrated Rock (Stratum C) below the pavement materials, existing fill, or residual soils in seven test borings to depths 0.7 to 5 ft below the pavement surface.

• Groundwater was observed during drilling in boring PCB-01 at a depth of 2 ft below the pavement surface. We believe this represents perched water since it was only observed within the existing coarse-grained fill soils and was not encountered at any other boring locations.

• Based on laboratory test results, the fill soils of Stratum A are expected to be non-corrosive to buried metallic structures based on the American Water Works Association (AWWA) ranking system. However, the natural soils of Strata B and C are considered potentially corrosive to buried metallic structures based on AWWA. We recommend that all underground drainage structures be designed based on an aggressive subsurface environment for buried metals. All soil samples tested for sulfate content had negligible levels of sulfates and special sulfate resistant cement is not expected to be necessary for buried concrete structures.

• We observed debonding, that we believe to be associated with pavement fatigue or deterioration, in 4 of 21 pavement cores performed for the project. This was generally observed at the interface between the asphalt surface layer and the base layers and was observed at depths of 1.5 and 2.5 inches along Park Central Road and 3 and 3.5 inches along Foxville Deerfield Road.

• Based on our subconsultant, Advanced Infrastructure Design’s (AID), automated pavement condition survey and PCR calculations, the average condition in both lane directions of Foxville- Deerfield Road is considered to be poor (PCR<60) from Milepost (MP) 0 (STA 10+84) (Foxville Church Road) to MP 1.08 (STA 67+60 - Saw Mill site) and in good condition (85<PCR<95) from MP 1.08 (STA 67+60) (Saw Mill site) to MP 1.86 (STA 109+47 - End of Park property). PCR results for Park Central Road measured poor pavement conditions between MP 0 (STA 394+00 - MD 77) to MP 0.2 (STA 384+00), fair pavement condition from MP 0.2 (STA 384+00) to MP 2.52 (STA 260+50 - Camp 3), and poor pavement condition from MP 2.52 (STA 260+50 - Camp 3) to MP 3.66 (STA 200+00 - Manahan Road). PCR maps are included in Appendix C.

April 5, 2022 Page 2 Schnabel Engineering, LLC

• Based on the observed pavement condition, traffic loading information, and subsurface data collected, we recommend a combination of either deep mill and overlay or full depth replacement for Park Central Road between MP 0.0 and 0.2 (STA 394+00 and STA 384+00), mill and overlay between MP 0.2 and 2.52 (STA 384+00 and STA 260+50), and complete pavement replacement between MP 2.52 and 3.66 (STA 260+50 and STA 200+00).

• For Foxville-Deerfield Road, we recommend complete pavement replacement between MP 0 and

1.08 (10+84 and 67+60) and a thin mill and overlay from MP 1.08 to 1.86 (STA 67+60 to STA 109+47). We also recommend localized repairs (patching) in areas where structural distresses are observed.

• We recommend that the existing grass shoulders along Foxville-Deerfield Road between MP 0 and 1.08 and Park Central from MP 2.52 to 3.66 be rebuilt with an aggregate-topsoil shoulder supported on graded aggregate base.

• A qualified pavement/geotechnical engineer must inspect the pavement surface before and/or after the milling operation is finished in order to identify patch locations. The project documents should consider add/deduct prices for more or less patches during construction.

• A qualified geotechnical engineer must verify the suitability of the shoulder subgrades before reconstruction. The project documents should consider add prices for undercutting and repair of unsuitable shoulder subgrades.

April 5, 2022 Page 3 Schnabel Engineering, LLC

2.0 SCOPE OF SERVICES

Our revised proposal dated March 15, 2020 defines the scope of services which is based on the project SOW. Our scope of services included a subsurface exploration, conducting a semi-automated pavement condition assessment, associated laboratory testing and preparing this geotechnical and pavement engineering report. This report includes:

• Estimated subsurface conditions, asphalt thicknesses, and groundwater levels within the area explored based on data collected in the subsurface exploration.

• Tables and maps indicating the results of the pavement condition assessment.

• A map showing the plotted pavement condition segmented along the roadways.

• Photographs of the collected pavement cores, and representative conditions of the roadway surfaces

• Observations and recommendations for roadway surface and subsurface drainage measures.

• Up to three options to rehabilitate, replace, or overlay the existing asphalt, depending on the observed pavement thickness and condition of the pavement. The pavement sections were designed in accordance with AASHTO 1993.

• Earthwork recommendations for the construction of load-bearing fill including an assessment of on-site soils for use as fill, pavement subgrade preparation, and compaction criteria.

• Construction considerations related to the implementation of our recommendations.

April 5, 2022 Page 4 Schnabel Engineering, LLC

3.0 DESCRIPTION OF SITE AND PROPOSED CONSTRUCTION

3.1 Site Description

The project includes asphalt pavement reconstruction and rehabilitation for segments of Foxville Deerfield Road and Park Central Road, as well as two parking areas and one turn around located off Park Central Road. Both the roadways, parking areas, and turn around are located within Catoctin Mountain National Park (CATO), which is managed by the National Park Service (NPS), near Thurmont, Maryland. Foxville Deerfield Road is a 1.86 mile, two-lane, asphalt paved roadway that runs along the western edge of the park from Foxville Church Road to the northern park boundary. Park Central Road is a 3.66-mile, two lane, asphalt paved roadway that runs between Manahan Road to the west and Maryland Route 77 to the east. About 50 percent of Park Central road alignment includes concrete curbs on one or both sides of the road, with the curbs ending at off-road inlets outside of the travel lane area. Park Central Road provides access to various camps including Camp David and other recreation areas. The project includes two paved small parking areas and a paved turnaround along Park Central Road. The areas surrounding these roadways are heavily wooded and the roadway grades are gently sloping. The average lane width for Park Central is 10 ft wide and Foxville-Deerfield Road’s average width is typically 9 ft wide with no shoulders. The ground surface grades drop off of the shoulders into shallow drainage swales in most locations. There is a gravity sewer line running down Park Central Road from Camp 3 to Manahan Road. The manhole covers are observed within the roadway.

Schnabel obtained the site information from the plans and reports provided by WSP, from our onsite observations during our pavement condition survey and subsurface exploration, and through our review of available site aerial imagery.

3.2 Proposed Construction

The project includes the preservation, reconstruction, and rehabilitation of Foxville-Deerfield Road and Park Central Road located within CATO. In addition, two parking areas and a turn-around along Park Central Road will be rehabilitated. The RFP documents included a design scoping report that identified the following anticipated construction activities:

• Full depth replacement of Foxville-Deerfield Road for approximately 1.1 miles between Foxville

Church Road to the Sawmill Site within the park boundary.

• Preservation of Foxville-Deerfield Road with a thin overlay for approximately 0.76 miles north of the

Sawmill site to the northern park boundary.

• Rehabilitation consisting of a shallow mill and overlay for approximately 0.2 miles of Park Central

Road between Maryland Route 77 and the maintenance parking area, at the park entrance.

• Rehabilitation consisting of mill and overlay for approximately 2.3 miles of Park Central Road located between 0.2 miles north of Maryland Route 77 and Camp 3.

• Full depth replacement of Park Central Road for approximately 1.2 miles between Camp 3 to the east and Manahan Road to the west.

• Mill and overlay of the Wolf Rock Parking Area, Park Central Picnic Parking Area, and the Camp 3 turnaround.

Based on the results of our study, the recommended treatments we identified generally agree with the recommendations included in the design scoping report, except that we recommend a deep mill and

April 5, 2022 Page 5 Schnabel Engineering, LLC replacement of the existing Park Central Road Pavement between Route 77 and the maintenance parking area. Additionally, we anticipate that partial and full depth patching will be required for segments of Foxville-Deerfield Road and Park Central Road. Section 7.0 of this report describes our specific pavement recommendations.

Additional improvements identified in the design scoping report included widening or installing new full depth shoulders and installing a roadside ditch along Foxville-Deerfield Road. The design scoping report also indicated that culvert replacements were necessary for Park Central Road.

Based on our correspondence with WSP, we understand that construction of new stormwater management facilities within CATO, and constructing new asphalt shoulders along Foxville-Deerfield Road are not feasible nor desired by the National Park Service (NPS). The soil surfaces and associated slopes will be repaired, stabilized, and regraded, where necessary, to support the edge of the existing and new pavements.

3.3 Traffic Data

Traffic loading was estimated based on the published traffic counts available on the NPS website for CATO and the information provided to us by the Eastern Federal Lands in the Design Scoping Report.

The traffic counts indicate an Average Annual Daily Traffic (AADT) of 612 vehicles in 2020 at the Visitor Center, which was considered for Park Central Road, and an AADT of 329 at Foxville-Deerfield Road.

Considering a 2% growth rate, we calculate a 2022 AADT of 342 vehicles for Foxville-Deerfield Road and an AADT of 637 vehicles for Park Central Road. Based on the Design Scoping Report, we considered 1% single unit trucks (FHWA Class 5 through 7) and 1% buses or tractor trailer vehicles (FHWA Class 4 and 8 through 13) for both roadways.

3.4 Regional Geology

Based on our experience in the area and review of geologic maps, both Foxville-Deerfield road and Park Central road are underlain by late Precambrian age rocks of the Catoctin Formation. The Catoctin Formation consists primarily of metamorphic formed rock of metabasalt, matarhyolite, and phyllite. The bedrock is overlain by residual soils and disintegrated rock derived from the weathering of the parent bedrock. Existing fill soils were found in several of our test borings above natural residual soils and bedrock. The existing fill soils are likely associated with the construction and grading of the existing roadways. A Geologic Map is included as Figure 2.

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4.0 SITE EXPLORATION PROGRAM

We conducted a site assessment and subsurface exploration program to evaluate the existing pavement condition, identify the subsurface stratigraphy underlying the site, and to evaluate the geotechnical properties of the materials encountered. This program included an automated Pavement Condition Survey (PCS) of the existing pavements in order to determine the Pavement Condition Rating (PCR) in accordance with NPS’ Methodology for Determining Condition Ratings with the Data Collection Vehicle (DCV). Exploration methods used are discussed below. Appendices A through E include the results of our pavement condition assessment and the subsurface exploration program.

4.1 Test Borings and Pavement Cores

Schnabel’s subcontractor, Connelly & Associates, Inc. (Connelly), drilled 32 test borings (PCB-01 through PCB-21 and PB-01 through PB-11) and drilled 21 pavement cores (PCB-01 through PCB-21). The locations identified as ‘PCB’ were test locations where both a soil test boring and a pavement core were conducted. Pavement cores were not collected at the ‘PB’ locations.

The test boring locations were positioned along the roadway alignment to obtain subsurface information of the entire roadway, with greater frequency selected in the areas where the PCR indicated poor pavement conditions. Standard Penetration Tests (SPTs) were performed at selected depths in the test borings. This subsurface exploration was performed under our direct observation on September 20 through October 1, 2021. These pavement/core and pavement boring locations are shown on the Boring Location Plans included as Figures 3A to 3H at the end of this report.

Appendix A includes specific observations, remarks, and logs for the borings; classification criteria; drilling methods; approximate test boring and pavement core locations; pavement core photographs; and sampling protocols. Table A1, included in Appendix A, presents the coordinates and drilling depths for each boring and pavement core performed.

4.2 Pavement Condition Assessment

Our subconsultant, Advanced Infrastructure Design (AID), performed an automated pavement condition assessment on June 15, 2021 along Foxville-Deerfield Road and Park Central Road using their Integrated Testing Vehicle (ITV). The ITV captured high resolution video images; as well as continuous IRI, rut depth, faulting, and surface distress measurements using a Laser Crack Measurement System (LCMS). This data was collected, processed, and summarized for 0.02-mile segments of each roadway in each lane direction. The data was then interpreted further to calculate a pavement condition rating (PCR) for each roadway segment. The results of this automated condition assessment are presented on the figures and summarized in the tables included in Appendix C.

In addition, Schnabel conducted a visual pavement condition assessment of the Wolf Creek and Park Central Picnic parking areas and the Camp 3 turnaround. The results of this survey are discussed in Section 7.1 and are shown on the figures included in Appendix C. Further details regarding AID’s testing equipment, data collection methods, and data analysis methods are presented in Appendix E of this report.

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4.3 Ground Penetrating Radar

Ground Penetrating Radar (GPR) was performed for Foxville-Deerfield and Park Central Roads during the June 15, 2021 pavement condition survey using two high frequency air-launched, horn antennas attached to AID’s ITV. The GPR data was processed by AID and was calibrated based on the results of the asphalt coring performed during our subsurface exploration.

Based on the results of this analysis, AID prepared continuous profile plots of the asphalt pavement thickness for Foxville-Deerfield and Park Central Roads in each lane direction. The results of the GPR testing, further details of the equipment utilized, and the continuous profile plots of asphalt pavement thickness are presented in the AID’s summary report included in Appendix E.

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5.0 SOIL LABORATORY TESTING

Our soils laboratory in Baltimore, Maryland, performed tests on selected soil samples collected during the subsurface exploration in accordance with AASHTO and ASTM standards. This testing included index properties, moisture density relationships (Proctor), CBR, and corrosivity tests on samples collected from the soil test borings. The testing aided in the classification of materials encountered in the subsurface exploration and provided data for use in the development of our recommendations. The results of the laboratory tests are included in Appendix B and are summarized for each stratum in the Section 6.1 of this report. Selected test results are also shown on the boring logs in Appendix A.

5.1 Index Testing

We performed natural moisture content (AASHTO T265), Atterberg Limits (AASHTO T89 and T90), and gradation tests (AASHTO T88) on samples of the soils and disintegrated rock of Strata A, B, and C, to provide soil classifications of the soil materials encountered at pavement subgrades and to allow for correlations with published soil properties.

5.2 Compaction and CBR Testing

We performed Standard Proctor compaction (AASHTO T99) and CBR testing (AASHTO T193) on six bulk samples representing Strata A and B to evaluate compaction characteristics and to provide soil parameters for pavement analysis and design.

5.3 Corrosivity Testing

We performed testing on nine soil samples for pH (AASHTO T289), sulfides (AWWA), redox potential (ASTM G200), and resistivity (AASHTO T288) on samples collected from Strata A, B and C. Our subcontractor, Phase Separation Science, performed water-soluble sulfate and chloride tests (EPA 300.0) on the same soil samples.

April 5, 2022 Page 9 Schnabel Engineering, LLC

6.0 SITE GEOLOGY, PAVEMENT, AND SUBSURFACE CONDITIONS

6.1 Site Geology

During our exploration, we encountered existing fill soils, residual soils, or disintegrated rock directly below the existing asphalt pavement or aggregate base. The existing fill soils, identified as Stratum A, are believed to have been placed during past earthwork operations for roadway construction. The residual soils, identified as Stratum B, were encountered either below the existing fill of Stratum A or the pavement materials. The disintegrated rock of Stratum C was observed either below the pavement surface, the existing fill of Stratum A or the residual soil of Stratum B. The residual soils and disintegrated rock are derived from the in-place weathering of the underlying parent bedrock.

6.2 Generalized Subsurface Stratigraphy

We characterized the following generalized subsurface stratigraphy based on the exploration and laboratory test data included in the appendices. The stratum assigned to each soil layer is shown on the boring logs and is based on our site reconnaissance, observations of soil samples, and published geologic maps.

6.2.1 Existing Asphalt Pavement

Asphalt pavement was encountered at the ground surface in each boring and pavement core performed.

The existing pavement section either consisted of asphalt pavement placed directly on the soil subgrade or asphalt pavement above aggregate base. Within Foxville-Deerfield Road, the asphalt pavement section was measured to be between 8.5 and 11 inches thick in the borings or cores. Based on our review of the GPR results, the asphalt thicknesses appears to vary between 8 and 12 inches along Foxville Deerfield Road. Dense graded aggregate (DGA) was only observed in borings and cores PCB- 19 and PCB-20 below the asphalt pavement and was measured to be 6 and 7 inches in thickness. The remaining borings collected along Foxville-Deerfield Road did not encounter aggregate base and we observed asphalt pavement directly above the soil subgrade.

Within Park Central Road, we observed asphalt core thicknesses that varied between 4.5 and 8.5 inches.

The GPR test results indicated asphalt thicknesses between 6 and 9 inches from MP 0 to 2.52 (STA 394+00 to STA 260+50) and between 4 and 5 inches from MP 2.52 to 3.66 (STA 260+50 to STA 200+00). Aggregate base was encountered in borings and cores PB-01, PB-04, PB-06, PB-07, PCB-01, PCB-09, PCB-10, PCB-11, PCB-12, and PCB-14 with thicknesses that varied between 4 and 15 inches.

The remaining borings and cores performed within Foxville-Deerfield Road did not encounter aggregate base below the asphalt pavement, and it appears that the majority of the existing Park Central Road pavement between Route 77 and Camp 3 is supported directly on the soil subgrade.

Debonding was observed in approximately 50 percent of the pavement cores collected; however, the majority of this debonding is believed to be associated with mechanical breaks associated with the pavement coring. Four of the pavement cores, including PCB-01 and PCB-02 along Park Central Road as well as PCB-17 and PCB-18 along Foxville-Deerfield Road, were believed to have exhibited debonding associated with distress and deterioration at the interface between the surface asphalt pavement and the underlying base layers. Photographs of these cores are included in Appendix A.

April 5, 2022 Page 10 Schnabel Engineering, LLC

Table A2, included in Appendix A, summarizes our measurements of the existing asphalt and aggregate base at each core and boring location. Photos of the extracted cores are also included in Appendix A.

Profiles of the GPR test results are presented in AID’s summary report included in Appendix E.

6.2.2 Stratum A: Existing Fill

Below the asphalt pavement and aggregate base, we encountered the existing fill material (designated as Stratum A) in 12 of the borings to depths of 1.5 ft to 5 ft. The existing fill material visually classified as LEAN CLAY (CL), CLAYEY GRAVEL (GC), and CLAYEY SAND (SC), per the Unified Soil Classification System (USCS), with varying amounts of sand, and gravel sized rock fragments. The SPT N-values within the existing fill soils ranged from 6 bpf (blows per foot) to greater than 100 bpf.

Laboratory tests performed on eight samples of soil collected from Stratum A had Liquid Limits ranging from 29 to 40 and Plasticity Indices ranging from 10 to 18. The percentage passing a No. 200 sieve was measured between 17.2 and 55.5 percent. The natural moisture contents of samples of Stratum A varied between 5.6 and 26.1 percent, and are reported on the boring logs.

Chemical testing was performed on two soil samples of Stratum A to evaluate the corrosivity of these soils. The chemical testing measured a pH value of 7.27 and 7.56, Redox Potential value of 46 and 79 mV, Resistivity value of 2,300 and 2,900 ohm-cm, and a negative test for sulfides. Chloride and sulfate ion tests performed on the soil samples measured from non-detected to 93 ppm of chlorides and 94 to 98 ppm of sulfates.

Based on these test results, the soils of Stratum A are considered to be non-corrosive to buried metallic structures in accordance with AWWA rankings and are considered to be non-corrosive for steel structures in accordance with AASHTO LRFD Bridge Design Specifications. The results of sulfate content testing indicate negligible levels of sulfates in accordance with ACI standards. According to these results, drainage structures to be built within the soils of Stratum A should be designed based on an aggressive subsurface environment for buried metals. Our corrosivity calculations are included in Appendix F.

6.2.3 Stratum B: Residual Soils

Underlying the existing pavement layers or the existing fill soils of Stratum A, we encountered the residual soils (designated Stratum B) in 25 of the borings to depths ranging from 2.2 ft to 10 ft below the ground surface, the maximum depth reached. Stratum B soils consisted of CLAYEY GRAVEL (GC), CLAYEY SAND (SC), LEAN CLAY (CL), and SILT (ML) per the USCS, and contained varying amounts of sand, and gravel sized rock fragments. The residual soils of Stratum B had SPT N-values ranging from 5 to greater than 100 bpf.

Chemical testing was performed on five soil samples of Stratum B to evaluate the corrosivity of these soils. The chemical testing measured a pH value ranging between 6.98 and 7.64, Redox Potential values between 13 and 173 mV, Resistivity values ranging between 670 and 2,700 ohm-cm, and a negative test for sulfides. Chloride and sulfate ion tests performed on the soil samples measured from 76 to 960 ppm of chlorides and from not detected to 83 ppm of sulfates.

Based on these test results, the soils of Stratum B are considered potentially corrosive to buried metallic structures in accordance with AWWA standards, are considered to be potentially corrosive for steel structures in accordance with AASHTO LRFD Bridge Design Specification, and have negligible levels of

April 5, 2022 Page 11 Schnabel Engineering, LLC sulfates in accordance with ACI standards. According to these results, drainage structures to be built within the soils of Stratum B should be designed based on an aggressive subsurface environment for buried metals. Our corrosivity calculations are included in Appendix F.

6.2.4 Stratum C: Disintegrated Rock

Below the existing fill soils of Stratum A we encountered disintegrated rock (designated Stratum C) in seven borings at a depths between 0.7 and 5 ft. Disintegrated rock is defined as residual material with SPT N-values between 60 blows per foot and refusal. Refusal is defined as an N-value of 50 blows for a penetration of one inch or less. The disintegrated rock of Stratum C was visually classified as LEAN CLAY (CL) and CLAYEY GRAVEL (GC) and contained varying amounts of sand, and rock fragments.

The SPT N-values measured within this stratum were greater than 60 bpf.

Eleven of the test borings encountered auger refusal at depths ranging from 1.3 to 8.5 ft below the ground surface. We believe the augers likely refused on the underlying parent bedrock.

Chemical testing was performed on one soil sample of Stratum C to evaluate the corrosivity of these soils.

The chemical testing measured a pH value of 7.22, Redox Potential 120 mV, Resistivity value of 1000 ohm-cm, and a negative test for sulfides. Chloride and sulfate ion tests performed on the soil sample measured 470 ppm of chlorides and 91 ppm of sulfates.

Based on these test results, the soils of Stratum C are considered potentially corrosive to buried metallic structures in accordance with AWWA standards, are considered to be potentially corrosive for steel structures in accordance with AASHTO LRFD Bridge Design Specification, and have negligible for sulfates in accordance with ACI standards. According to these results, drainage structures to be built within the soils of Stratum C should be designed based on an aggressive subsurface environment for buried metals. Our corrosivity calculations are included in Appendix F.

6.3 Groundwater

Groundwater was observed during drilling in boring PCB-01 at a depth of 2 ft below the pavement surface. We believe this represents perched water since it was only observed within the existing coarse-grained fill soils and was not encountered at any other boring locations. Long-term water level readings were not taken as the borings were backfilled upon completion for safety reasons.

The groundwater levels on the logs indicate our estimate of the hydrostatic water table at the time of our subsurface exploration. Variation in groundwater levels may occur depending on variation in precipitation, surface runoff, leaking utilities, lake levels, and similar factors.

6.4 Moisture Density Relationship and CBR Testing

Standard Proctor compaction and CBR tests were performed on six bulk soil samples collected from borings PCB-07, PCB-09, PCB-11, PCB-13, PCB-15, and PCB-18. These samples generally classified as CLAYEY SAND (SC), LEAN CLAY (CL), and SILT (ML) with varying amounts of sand and gravel sized rock fragments. Liquid Limits for these samples ranged between 28 and 47 and Plasticity Indices between 11 and 18. These samples had percentages passing the No. 200 sieve ranging between 37.6 and 56.9 percent.

April 5, 2022 Page 12 Schnabel Engineering, LLC

The results of Standard Proctor testing obtained maximum dry densities between 115.2 to 135.1 pounds per cubic foot (pcf) at optimum moisture contents of 15.1 and 10.9 percent, respectively with the exception of PCB-15 that had a maximum dry density of 109.8 at an optimum moisture content of 17.1.

The results of CBR testing measured CBR values generally ranging between 2.7 and 4.8; and swell percentages ranging from 0.1 to 0.9 percent with the exception of PCB-15 that had a CBR value of 1 and swell percentage of 3 percent.

April 5, 2022 Page 13 Schnabel Engineering, LLC

7.0 PAVEMENT ANALYSES AND RECOMMENDATIONS

7.1 Pavement Condition Assessment

Schnabel’s subcontractor AID performed an automated pavement condition survey of the existing pavements along Foxville-Deerfield and Park Central roads in accordance with the “Standard Practice for Quantifying Cracks in Asphalt Pavement Surfaces from Collected Pavement Images Utilizing Automated Methods (AASHTO R 85-18)”. The data collection was performed on June 15, 2021 to estimate the Pavement Condition Rating (PCR). As previously indicated, the PCR was determined for 0.02-mile segments within each lane direction. The results of this condition assessment are summarized in Pavement Condition Rating results tables included in Appendix C. This data is summarized for 0.1-mile segments of roadway in each lane direction on Figures C1 and C2, also included in Appendix C. AID’s entire report is included in Appendix E.

Based on our interpretation of the data, we generalized the pavement condition for segments of Foxville- Deerfield Road and Park Central Road where there were apparent trends in the severity of the observed distress and the PCR ratings. The following sections summarize the typical distresses encountered and the average PCR rating for each lane direction observed during our pavement condition survey of Foxville-Deerfield Road, Park Central Road, and the parking areas and turnaround along Park Central Road.

The general condition and average PCR observed along these segments are shown on Figures C3 and C4. Photographs of the predominant pavement distresses observed during our condition assessment are included in Appendix D. Please note that our assessment depicts the pavement surface conditions observed only at the specific locations and times indicated. We expect that the pavement condition will change with the passage of time.

7.1.1 Foxville Deerfield Road

MP 0 (STA 10+84 - Foxville Church Road) to MP 1.08 (STA 67+60 - Sawmill Site): The roadway along this segment had an average PCR of 54 in the northbound direction and an average PCR of 63 in the southbound direction, with an overall average PCR of 58 which is considered to be poor condition. The predominant pavement distresses we observed include medium to high severity fatigue cracking, cold-patches with severities ranging from low to high, and medium severity edge cracking at some locations.

Much of the edge cracking was observed in the northbound direction, and is believed to be related to wheel wander off of the asphalt pavement surface and onto the unpaved shoulder areas.

MP 1.08 (STA 67+60 - Sawmill Site) to MP 1.86 (STA 109+47 - Northern CATO Boundary): The roadway along this segment had an average PCR of 82 in the northbound direction and an average PCR of 89 in the southbound direction, with an overage average PCR of 85 which is considered to be good condition.

The predominant pavement distresses we observed included low severity longitudinal and transverse cracking, isolated locations with low to medium severity fatigue cracking and cold-patches, and low severity edge cracking. These distresses were observed in less than 5% of the roadway area.

7.1.2 Park Central Road

MP 0 (STA 394+00 - Route 77) to MP 0.2 (STA 384+00): The roadway along this segment had an average PCR value of 56 in both the eastbound and southbound directions which is considered to be

April 5, 2022 Page 14 Schnabel Engineering, LLC poor condition. The predominant pavement distresses observed include medium to high severity fatigue cracking and medium severity cold-patches.

MP 0.2 (STA 384+00) to MP 2.52 (STA 260+50 - Camp 3): The roadway along this segment had an average PCR value of 78 in the westbound direction and an average PCR value of 82 in the eastbound direction, with an overall average PCR of 80, which is considered to be in fair condition and just slightly below a good condition (PCR=85+). The predominant pavement distresses observed include low to medium severity fatigue cracking, low severity rutting, and cold-patches with severities ranging from low to high. These distresses were observed in less than 5% of the roadway area. Around MP 2.02 (STA 286+59), we observed a high severity patch above a culvert location, which appears to have corrected settlement associated with the culvert installation. This patch appears to have been in place for a long period, since striping has been repainted above the cold patch. The roadway does not appear to have settled further after placement of this cold patch.

MP 2.52 (STA 260+50 – Camp 3) to MP 3.66 (STA 200+00 - Manahan Road): This segment of the roadway had an average PCR value of 50 in the westbound direction and an average PCR value of 52 in the eastbound direction, with an overall average PCR of 51 which is considered to be poor condition. The predominant pavement distresses observed include medium to high severity fatigue cracking, medium to high severity cold-patches, and low to medium severity edge cracking at some locations. The edge cracking was notably less severe along this segment of Park Central Road when compared to the edge cracking observed along Foxville-Deerfield Road. We anticipate that some of the edge cracking is associated with vehicles driving beyond the pavement edge and onto the unpaved shoulder, but there is less observable damage to the shoulder area along Park Central Road.

7.1.3 Park Central Parking Areas and Camp 3

Based on our September 10, 2021 visual pavement condition assessment, we consider the pavements at the Wolf Rock and Park Central Picnic parking areas to be in good condition with estimated PCR values of 90 and 85, respectively. The Wolf Rock Parking area was not observed to have considerable surface distresses. We observed one location with a low severity pothole as well as low severity raveling of the asphalt surface at the Park Central Picnic parking area.

We believe the pavement condition for Camp 3 Turn Around area is in poor condition with an estimated PCR of 45. We observed medium to high severity longitudinal and transverse cracks and high severity raveling of the asphalt surface as the predominant distresses.

7.2 Pavement Recommendations

We developed pavement recommendations in accordance with AASHTO 1993 design method for flexible pavements. The following design assumptions were used in our analysis, generally following parameters used by the Federal Highway Administration as specified in the Project Development and Design Manual (PDDM). Our analysis is included in Appendix F.

The traffic data described in Section 3.3, the results of our pavement condition assessment, and the pavement subgrade information collected during our subsurface exploration were used to develop our recommendations for the proposed pavement treatments. Based on the results of the CBR testing, we

April 5, 2022 Page 15 Schnabel Engineering, LLC considered a design CBR value of 2.5, corresponding to a subgrade resilient modulus of approximately 3,750 psi.

The design parameters used in our analyses are summarized in the table below. Unless noted in the table, the pavement design parameters were utilized for both Park Central and Foxville-Deerfield Roads, and parking areas.

Table 1: Pavement Design Parameters

Pavement Design Life Rehabilitation 20 years Reconstruction 25 years

Service life and Reliability Data Initial Serviceability Index 4.2 Final Serviceability Index (Foxville-Deerfield) – ADT < 500 2.0 Final Serviceability Index (Park Central Road) – 500 < ADT < 5,000 2.5 Standard Deviation 0.49 Pavement Reliability 75%

Traffic Load Data 2022 ADT (Foxville-Deerfield Road) 329 vehicles 2022 ADT (Park Central Road) 612 vehicles FHWA Class 4 (Buses) and Class 8-13 (Tractor Trailers) 1% FHWA Class 5 to 7 (Single Unit Trucks) 1% Annual Growth Percentage 2% Directional Distribution 60%

Pavement Layer Coefficients Asphalt Surface 0.44 Asphalt Intermediate and Base 0.40 Existing Asphalt Pavement 0.30 Existing Aggregate Base 0.10

Based on our evaluation of pavement condition assessment data, we considered that segments of the roadway that classified as “Poor” will require a major rehabilitation such as a deep mill and replacement or full depth pavement replacement. Segments that classified as poor included Park Central Road from MP 0 to 0.2 (STA 394+00 to STA 384+00), Park Central Road from MP 2.52 to 3.66 (STA 260+50 to STA 200+00), Foxville-Deerfield Road from MP 0.0 to 1.08 (STA 10+84 to STA 67+60), and the Camp 3 turnaround. We considered that pavement resurfacing and spot repairs would be necessary for roadways that classified as “Fair”, such as Park Central Road from MP 0.2 to 2.52 (STA 384+00 to STA 260+50).

For pavement sections that were in “Good” condition, we considered that isolated repairs such as crack sealing and localized patching, coupled with a minor depth resurfacing will be suitable. Foxville-Deerfield Road north of MP 1.08 (STA 67+60) was considered to be in “Good” condition.

The following tables and subsections identify our recommended treatment options and pavement alternatives for each section of Foxville-Deerfield Road and Park Central Road. Where full depth

April 5, 2022 Page 16 Schnabel Engineering, LLC replacement is not recommended, the tables below also include recommended full or partial depth patching sections based on the existing pavement thicknesses and an estimate of the gross square footage that may require patching, based on our site observations and the pavement condition data. All patches should extend the full lane width or the entire pavement width so that joints are not present below the wheel paths.

Where full depth pavement replacement is recommended, and there are no curbs, we recommend the new pavement edges be protected. Pavement safety edges will be constructed for the surface asphalt lift.

In addition, the shoulders outside of the safety edges should be strengthened.

New safety edges are not feasible where milling and overlays are recommended. However, following the new asphalt overlays, the shoulders outside of the pavement edges (where there is no curb) should be filled with the topsoil/aggregate mix to provide a shoulder surface level with the pavement edge.

7.2.1 Foxville-Deerfield Road: MP 0 (STA 10+84) to MP 1.08 (STA 67+60)

For Foxville-Deerfield Road between MP 0 and 1.08 (STA 10+84 to 67+60) we evaluated options including replacement of the existing pavement section, a deep mill and overlay with extensive patching, and full depth reclamation (FDR). We do not consider FDR to be a reasonable strategy since this segment of Foxville-Deerfield road is only asphalt surfaced with no aggregate base layer. Similarly, while feasible, a deep mill and overlay will likely not repair the edge cracking observed and we believe that significant patching with a full depth pavement section and regrading of the unpaved shoulder would be necessary. Therefore, we recommend full depth removal and replacement of Foxville-Deerfield Road between MP 0 and 1.08 (STA 10+84 to 67+60). The table below summarizes what we consider to be reasonable pavement options for this roadway section.

Table 2: Foxville-Deerfield Road from MP 0 (STA 10+84) to MP 1.08 (STA 67+60)

Layer Item Specification Layer Thickness (inch)

Option 1 – Full-depth Removal and Replacement Section

Asphalt Surface Gyratory mix, 1/2 inch (12.5mm) nominal maximum size aggregate, <0.3 million ESAL, PG64-22. Type IV roughness

Asphalt Base Gyratory mix, 3/4 inch (19mm) nominal maximum size aggregate, <0.3 million ESAL, PG64-22

Aggregate Base Graded Aggregate Base, CBR-80 5

Option 2 – Deep Mill and Replacement with Full Depth Patching (Type 2)

Mill Existing Asphalt Asphalt pavement milling -5.0

Asphalt Surface Gyratory mix, 1/2 inch (12.5 mm) nominal maximum size aggregate, <0.3 million ESAL, PG64-22. Type IV roughness.

2.0

Asphalt Base Gyratory mix, 3/4 inch (19mm) nominal maximum size aggregate, <0.3 million ESAL, PG64-22

3.0

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A tack coat should be applied between all asphalt lifts and on top of milled pavement surfaces. Tack coat application shall be in accordance with FP-14 Section 412.

7.2.1.1 Foxville-Deerfield Road Shoulder Strengthening

Based on our site observations, we believe that portions of Foxville-Deerfield Road between MP 0 (STA 10+84) and 1.08 (STA 67+60) are failing due to edge cracking due to vehicle wander off the existing pavement. For this area, the shoulders should be strengthened to fix the shoulder drop off, and protect the pavement edges. We understand that a safety edge will be constructed in areas of full-depth replacement. The top surface of the safety edge should be aligned with the current pavement edge, and then sloped onto the existing shoulder. The new aggregate base and the new asphalt base must be extended laterally a few inches to be fully constructed below the safety edge.

Outside of the safety edge, the new shoulders should be strengthened with a mixture of aggregate topsoil mix, placed above a layer of dense graded aggregate to create a “hard running” shoulder section. This strengthened shoulder section should extend at least a two feet width on both sides of the roadway and should be excavated to a depth of at least one foot and backfilled with dense graded aggregate base material followed by 3 inches depth of aggregate-topsoil mix at the surface to align with the roadway.

The shoulder subgrade soils should be observed and approved by a geotechnical engineer. If weak subgrade soils are encountered at the depth of undercut for the shoulder, we recommend at least one foot of additional undercut backfilled with dense graded aggregate material. The new shoulder section should be constructed to extend from the edge of the proposed new pavement section. The shoulder reconstruction and materials shall meet Section 313 of the FP-14 Standard Specifications.

7.2.2 Foxville-Deerfield Road: MP 1.08 (STA 67+60) to MP 1.86 (STA 109+47)

For Foxville-Deerfield Road between MP 1.08 and 1.86 (STA 67+60 and STA 109+47), the roadway was observed to be in good condition with minor areas of low severity transverse and longitudinal cracking and areas of low to medium severity fatigue cracking. We recommend that preservation treatments be used for this segment of Foxville-Deerfield Road. As a minimum treatment, we recommend that the areas exhibiting low severity cracking be crack sealed. For moderate severity cracks and cold-patch areas, we recommend a partial depth patch to help decelerate the rate of pavement deterioration. For the entirety of the roadway, we recommend that the pavement be micro-milled and a thin overlay be placed above the micro-milled pavement surface to create a new pavement appearance without building up the section.

The table below summarizes our recommended preservation treatment and includes a recommended partial depth patch section.

April 5, 2022 Page 18 Schnabel Engineering, LLC

Table 3: Foxville-Deerfield Road from MP 1.08 (STA 67+60) to MP 1.86 (STA 109+47)

Layer Item Specification Layer Thickness (inch)

Pre-Overlay Repairs followed by Micro-milling and Thin Overlay

Mill Existing Asphalt Surface Asphalt pavement milling, 3/4-inch (19mm) depth -0.75

Asphalt Surface Gyratory mix, No.4 sieve (4.75mm) nominal maximum size aggregate, PG64-22. Type IV roughness 0.75

Partial-depth Patch Section (Type 3): Est. Quantity of 5,100 square feet

Mill Existing Asphalt Asphalt pavement milling Min. 2.751

Asphalt Surface 1 Gyratory mix, No.4 sieve (4.75mm) nominal maximum size aggregate, PG64-22. Type IV roughness.

0.75

Asphalt Surface 2 Gyratory mix, 1/2 inch (12.5mm) nominal maximum size aggregate, <0.3 million ESAL, PG64-22

Min. 2

1. Milling depth for partial depth patching should extend through the existing surface lift asphalt pavement.

Where distresses are observed at the pavement surface, we recommend partial depth patches. The patches should extend the full lane width or the entire pavement width. We estimate that approximately 5,100 square feet of this segment of Foxville-Deerfield Road will require a partial depth patch to repair the road surface. We have based this quantity on the results of the survey performed by our subcontractor AIDPE on June 15, 2021 and our own visual patching survey performed in September 10, 2021. Our estimated quantities are included in a table at the end of Appendix C.