Technical Report - AC-901579_HWY-107.pdf

Submitted by:

Barrett Hale & Alamo, LLC

Calle Del Parque #207

San Juan, PR 00912

PO Box 6425

San Juan, PR 00914-6425

Phone 787.982.7050

Fax 787.982.7056

TECHNICAL REPORT

ER-HWY-107

AC-802544

PR-124, Km. 22.35

MUNICIPALITY OF LARES

LANDSLIDE AND ROAD DAMAGE

EVALUATION AND REPAIR

RECOMMENDATIONS

EMERGENGY RELIEF PROGRAM

PUERTO RICO HIGHWAY AND

TRANSPORTATION AUTHORITY

April 8, 2019

Technical Report Page i Landslide and Road Damage Evaluation and Repair Recommendations ER-HWY-107: PR-124, Km. 22.35 AC-802544

TABLE OF CONTENTS

1. INTRODUCTION

1.1. Project Location

1.2. Highway Design Criteria

2. DAMAGE ASSESSMENT

3. WORK EXECUTED

3.1. Field Survey

3.2. H-H Studies

3.3. Geotechnical Studies

3.4. Maintenance of Traffic Evaluation and TMP Determination

3.5. Environmental Overview

4. TECHNICAL SOLUTION ALTERNATIVES

4.1. Alternative A (New Gabion Retaining Wall)

4.2. Alternative B (MSE Wall with Gabion Facing)

4.3. Alternative C (Reinforced Concrete Cantilever Wall)

5. ALTERNATIVES EVALUATION

5.1. Construction Cost

5.2. Constructability

5.3. Construction Time

5.4. Solution Complexity

5.5. ROW Impact

5.6. Environmental Considerations

5.7. Impact on Utilities

6. RECOMMENDATIONS

APPENDIX A: Plans for Technical Solution Alternatives

APPENDIX B: Survey Plans for Project Site

APPENDIX C: Preliminary Environmental Evaluation Technical Memorandum

APPENDIX D: Geotechnical Engineering Report

APPENDIX E: Construction Cost Opinion of Alternatives

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LIST OF TABLES

Table 1: Significant Projects Criteria

Table 2: Recommended Distance Between Signs

Table 3: Recommended Distance of Tapers at Work Areas

Table 4: Recommended Distance of Work Areas

Table 5: Affected Parcels by the Proposed Actions

Table 6: Comparison of Alternatives for ER-HWY-107

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LIST OF FIGURES

Figure 1: Location Plan

Figure 2: Roadway Condition, Looking East

Figure 3: Landslide Area, Looking West

Figure 4: Landslide Area, Looking SouthEast

Figure 5: Landslide Area, Looking South

Figure 6: Roadway Condition, Looking North East

Figure 7: Maintenance of Traffic Typical Example

Figure 8: Historic and Archeological Resources Map

Figure 9: Water Resources and Wetlands Map

Figure 10: Threatened and Endangered Species and Wildlife Habitat Map

Figure 11: FEMA Flood Zone Map

Figure 12: Affected Parcels by the Proposed Actions (Source: Catastro Digital – CRIM)

Figure 13: Water Utilities in Project Site

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1. INTRODUCTION

After Hurricanes Irma and María impacted the island in September 2017, the Puerto Rico Highway and

Transportation Authority (PRHTA) has undertaken an Emergency Relief Program to repair the impacts associated with these events on the Puerto Rico highway system. As part of the efforts of the Emergency

Relief Program, the project “Landslide and Road Damage Evaluation and Repair Recommendations” was created in order to evaluate and reconstruct the landslides, slope instability, washouts and/or rockfalls that resulted from the hurricanes. Each location in the highway network where these kinds of damages have been identified with a unique project ID number. This Technical Report has been prepared for the following project:

Project ID LOCATION

ER-HWY-107 PR-124, Km. 22.35 Municipality: Lares, PR

The objective of this Technical Report is to document the reconnaissance and evaluation activities performed for this specific project with the goal of providing effective and feasible recommendations to reconstruct the road to its previous conditions, ensuring the safety and connectivity of this road user.

1.1.Project Location

The site for project ER-HWY-107 is located on the kilometer 22.35 of State Road PR-124, in the

Municipality of Lares. State Road PR-124 is a rural road considered part of the secondary road network, with an approximate length of 27.0 kilometers beginning at its intersection with State

Road PR-119 and PR-120 and ending at its intersection with State Road PR-111. PR-124 is a rural collector that connects several communities in the Municipality of Lares and Las Marías with the rural arterial State Road PR-111 which leads to in and out of the Municipality.

The Location Plan for site ER-HWY-107 is shown on Figure 1.

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Figure 1: Location Plan

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1.2.Highway Design Criteria

State Road PR-124 is an undivided two-lane roadway without shoulders, with an approximate roadway width of 5.50 meters. Based on this configuration, PR-124 may be classified as an R-10

Local Rural Road in accordance with PRHTA Highway Design Manual.

For this type of roadway, the following design criteria apply:

• Design Class Code: R-10

• Functional Highway Classification (AASHTO): Rural Local Road

• Functional Highway Classification (PRHTA): 2 Lane Local Rural Road

• Control of Access: None

• Average Daily Traffic: 1,200 vpd (Year 2002)

• Type of Terrain: Mountainous

• Design Speed: 20 MPH

• Maximum Grade: 12%

• Minimum Curve Radius: 30 meters

• Maximum Superelevation: 6%

• Design Vehicle: Single Unit (SU)

• Design Load for Structures: HL-93

The following design criteria will be considered during the development of alternatives and will govern the process for designing a final solution to the damages of this site:

Surveying

Surveying activities executed for the project and survey plans are signed by a Licensed Surveyor in Puerto Rico. The coordinates system used for the project is Puerto Rico Lambert Coordinates

System NAD-83. The official monuments or control points for the project were properly defined and identified. All distance and elevations are presented in meters in accordance to PRHTA requirements.

Surveying tasks are the responsibility and are to be completed by Pedro J. Dávila Colón (PJDC).

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Pavement Rehabilitation and Design

The scope of work for the Emergency Relief Program limits the pavement improvements to repairs of affected areas. Based on this limitation, pavement rehabilitation analysis and recommendations are considered outside the Scope of Work and only pavement repair recommendations will be considered for the project.

In the specific case of roadway and landslide repair projects, the pavement repairs shall consider full lane widths extending 5 meters from the edge of the affected area. Pavement sections to be proposed as part of the project repair shall be in accordance with PRHTA’s Design Directives.

Utilities and Lighting

In case that the affected area may require the relocation of utilities, such relocation design shall comply with the standards and requirements of PRHTA, PREPA, PRASA, and any other concerned agency. In addition, the relocation design shall be developed in accordance with the

PRHTA’s Master Utility Agreements with PREPA and PRASA, and any other utility company.

Structures

Structures shall be designed in accordance with the AASHTO LRFD Bridge Design Specifications

8th Edition, PRHTA Standard Specifications for Road Bridge Construction and PRHTA’s Design

Directives. Different alternatives will be considered for retaining walls based on the project characteristics and geotechnical recommendations with the intention of designing the most cost-effective and suitable alternative for the project.

Traffic and Highway Safety

A review of existing traffic data is to be used for determining the current traffic conditions of the project (ADT, DHV, K, % of trucks). This information is to be used for analyzing the possible solutions for the project. The safety conditions and compliance with current standards are to be evaluated for the project in order to determine how they were affected by the damages caused by the hurricane. The evaluation of existing roadside safety elements, pavement markings and signing will be considered in the preparation of final pavement marking and signing plans as well as general geometry plans.

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Maintenance of Traffic (MOT) plans with the different stages of construction will be prepared for the project. MOT plans shall comply with the Puerto Rico Department of Transportation and

Public Works “Work Zone and Mobility Policy” of September 2015.

Hydrologic and Hydraulic Study

At sites were deemed necessary due to their proximity or interaction with water resources, a detailed Hydrologic and Hydraulic (H-H) Study is to be performed. The H-H Study will investigate and describe the existing conditions and compare them to the proposed conditions to determine the effect of the proposed works on the hydraulic conditions of the area. The study will be performed in accordance with the Planning Board Regulation No. 13 and the Puerto Rico’s

Department of Natural and Environmental Resources latest guides. The H-H studies will be used to perform a Scour Study to provide a report with conclusions and recommendations regarding the scour effects and countermeasures on the proposed solutions.

Drainage

The drainage patterns of the project area shall be analyzed to determine the required improvements in order to provide a proper drainage system throughout the whole project segment, taking into consideration possible erosion damages in the future. The drainage system shall consider a 25 years frequency design flood for roadway surface drainage and roadside ditches or channels or a 50 years frequency design flood for cross drainage structures.

Erosion Control

A design for the installation of temporary and permanent erosion and sediment controls will be completed to protect water resources from pollution due to erosion and transportation of sediments. The design shall comply with the following objectives:

• Minimize the area disturbed by construction and development

• Provide provisions for containment of sediments during construction

• Restore and stabilize disturbed areas after project completion

• Provide permanent erosion, drainage and detention controls as applicable

Erosion control design will be included in the project drawings and will be in accordance with

PRHTA Standard Specifications and requirements.

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Geotechnical Investigation

A geotechnical investigation shall be performed to determine all the necessary final recommendations for design and construction of all structures and soil work for the project. The geotechnical studies, sampling, analysis and reports will cover several aspects of the project, including the geology of the area, boring logs analysis, foundation recommendations, slope stability, need for soil improvements, excavations recommendations, amongst others. A geotechnical report will be completed that will collect all the information performed as part of the geotechnical investigation.

Right of Way

Right of way (ROW) plans and corresponding reports will be prepared as part of the design development of the project. The ROW plans will include the existing ROW as well as any acquisition or construction easement needed for the project. Research of the affected properties will be completed required for the preparation of Right of Way plans.

Environmental

In order to develop and evaluate the different alternatives for the project, it is required to assess and evaluate the environmental conditions of the project area. An initial evaluation of

Environmental aspects is described in this Technical Report with the objective of defining the subsequent steps in order to complete an environmental evaluation in accordance with the requirements of the Environmental Studies Office (ESO).

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2. DAMAGE ASSESSMENT

The project site identified as ER-HWY-107 consists of a landslide on the southeast side of PR-124 as a result of the heavy rainfall during Hurricanes Irma and María in September 2017. The area of the landslide is a low point of elevation of the pavement in the area, with embankments at both sides of the roadway. The embankment at the north side do not shows sign of damages, mainly because the slope is flatter as it serves as an access to the back of a residency.

During inspections it was observed that safety drums and a small bituminous curb were installed as emergency countermeasures at the project location. Based on field observations and aerial photos after the hurricane, the landslide that took place at the southeast side of PR-124 affected the pavement section and the guardrail in the northbound lane of PR-124.

From inspecting the project area, it is apparent the roadway surface runoff is reaching a roadside ditch at south side of the PR-124 east approach, which consequently reaches the area where the landslide occurred. It appears that the water running through the ditch discharged directly into the low part and promoted the slope erosion and support of the landslide area.

During field inspections it was observed that an aerial electrical line is travelling through PR-124 and is near the landslide area. From the research done in the Planning Board Database, it was found that two

(2) potable water lines of 2” and 16” are passing through PR-124.

The proposed alternatives for this project will consider solutions to repair the landslide caused by the impacts of Hurricanes Irma and María and prevent that future damage to the roadway is caused during high intensity rainfall events by managing properly the surface runoff.

The following pictures are presented to describe the damages observed during field inspections:

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Figure 2: Roadway Condition, Looking East

Figure 3: Landslide Area, Looking West

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Figure 4: Landslide Area, Looking SouthEast

Figure 5: Landslide Area, Looking South

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Figure 6: Roadway Condition, Looking North East

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3. WORK EXECUTED

This Technical Report (TR) presents information from geotechnical, survey, environmental and engineering aspects. Studies and reports for several of these disciplines will be further developed during the design process of the project solution. The following Sub-sections are a summary of the findings by the preliminary studies.

3.1.Field Survey

A Field Survey was completed for this site by Pedro J. Dávila Colón (PJDC). The reader is referred to Appendix B where survey plans are included of the project area. The topography of the area may be described as mountainous. The embankment of the south side of PR-124 has a steep slope of approximately 0.65 horizontal units to 1 vertical unit (0.65H: 1V) at the point of the landslide. Beyond the landslide area, the embankment has a slope of approximately of 1.25 horizontal units to 1 vertical unit (1.25H: 1V).

From the pavement elevations illustrated in the survey plan, it is noted that the cross slope of the existing roadway at this point is of a typical normal crown. The survey plan for the site is shown in

Appendix B.

3.2.H-H Studies

From the field inspections and the analysis of the area, no impacts to or from water bodies is expected for the project solution. From this assumption, it is considered that a detailed H-H study is not warranted. However, the hydrology of the area will be considered when designing drainage solutions for the project area. This task will be of high importance considering that surface runoff can be a contributing factor for future slope instability. No drainage system was identified in this site.

3.3.Geotechnical Studies

A subsurface exploration has been performed at the project location in order to explore the geology of the area and provide preliminary geotechnical recommendations. In general, the subsurface exploration showed that the landslide site is found within soils residua of brown to gray tuff breccia with lesser amounts of lapilli tuff. These residua are overlain by a thin layer of earth fill material used for the construction of the roadway. A horizon of partly cemented clayey silts occupy almost the complete subsurface profile. The consistency of this horizon improves

Technical Report Page 12 with depth from medium states to stiff and hard conditions at the end of the exploration point at 35 feet of depth.

According to the geotechnical report, the surface residua at the site saturated, softened and crumbled while dragged by the induced seepage pressures. Considering the soils observed in the subsurface exploration, the use of a cantilever or gravity retaining wall is the first option for the site reconstruction. The geometry of the existing slope limits the practical advantage of implementing the excavation and backfill treatment. The use of a retaining system based on piling or drilling was disregarded as a result of the stiff soils found at the project site.

For additional information, the reader is referred to Appendix C for a Geotechnical Report prepared for the project site by GeoPractica, Inc.

3.4.Maintenance of Traffic Evaluation and TMP Determination

3.4.1. TMP Criteria

A Transportation Management Plan (TMP) is a more comprehensive approach to managing work zone safety and mobility by applying a set of coordinated strategies to minimize impacts of a project. A Federal Aid highway project such the site ER-HWY-107 reconstruction requires establishing whether a TMP is necessary by determining if this is a significant project. The criteria for identifying significant projects are set out in the following table:

Table 1: Significant Projects Criteria

A. Projects with one or more activities in a location that fulfills all of the following criteria:

a) More than tree (3) days

b) Intermittent or continuous lane, ramps or other facilities closure

c) On a roadway with ADDT within the project limits ≥ 35,000 vehicles per day

B. Projects on roadways with AADT within the project limits with an AADT < 35,000 vehicles per day, but may have detours and closures that will adversely affect the traffic operation of a nearby roadway with AADT ≥ 35,000 vehicles per day.

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Projects that do not meet the previously established criteria will be classified as non-significant project. TMP’s for non-significant projects shall consist as a minimum of a Maintenance of Traffic

Plan (Temporary Traffic Control Plan (TTC)) and may include Transportation Operations (TO) and Public Information (PI) strategies.

For those projects classified as significant, the TMP’s shall consist of a Maintenance of Traffic

Plan (Temporary Traffic Control Plan (TTC)) as well as Transportation Operations (TO) and

Public Information (PI) strategies.

3.4.2. TMP Project Evaluation

We have evaluated each of the criteria to establish the significance of the ER-HWY-107 site project and determine if it requires the development and implementation of a TMP. The results were as follows:

• The activities of this project will last for more than three days

• Intermittent or continuous lane closures are expected along the roadway

• The PR-124 is a primary roadway with an AADT of 4,400 vpd which is less than the

35,000 vpd established in the criteria. The proposed reconstruction project at the PR-124 will not adversely affect the traffic operation of any nearby main roadway.

According to the criteria assessed the project can be classified as a non-significant project.

However, there are no alternate routes that can be used during construction.

3.4.3. Maintenance of Traffic (MOT)

A Maintenance of Traffic (MOT) plan is required any time work is conducted within ER-HWY-107 site area. Maintenance of Traffic typical application to most maintenance operations will be developed and provided as part of the construction plans. These typical applications should be used as guidelines for the layout of traffic control devices within work zones.

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Figure 7: Maintenance of Traffic Typical Example

3.4.4. General Signing Guidelines

The general guidelines used for the development of the MOT plans are as follows:

• All traffic control devices in work zones must be crashworthy. The requirements and criteria can be found in the National Cooperative Highway Research Program (NCHRP), Report 350.

• It is required that Part 6 of the MUTCD be followed to ensure that the signs used in work zones meet current standards.

• For visibility, signs should be placed within six (6) to twelve (12) feet of the edge of the traveled lane or no closer than two (2) feet to the back of curb.

• Existing permanent signing in the work zone which conflicts with temporary signs shall be covered during the work operation. Sign covers shall be removed when the work operation ceases. Signs should be covered so that the reflective material is not damaged.

• Temporary signing shall be covered or removed when the work operation ceases.

• END ROAD WORK (G20-2) signs shall be used in all cases if the duration of a work zone is long-term stationary and intermediate-term stationary.

• It is important that the work zone be driven on a daily basis to ensure that the motorist will not be confused by the signing sequence, drums and that all flashing arrows are aimed correctly.

3.4.5. Warning Signs

• The minimum size of all diamond shaped warning signs is 36" x 36".

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• Reflectorized signing is required.

• The “advance signing sequence” will be according to typical application.

3.4.6. Sign Spacing – “D” Distances

The spacing between signs is based upon the permanently posted roadway speed, which is 30 mph along the PR-124. The sign spacing distances are minimums and may be adjusted to meet changing roadway and traffic conditions.

Table 2: Recommended Distance Between Signs

ROAD TYPE /

VELOCITY

Distance Between Signs

A B C

Rural Segments V < 35 mph 100 m 100 m 100 m

3.4.7. Tapers – “L” Lengths

Whenever tapers are to be used near interchange ramps, crossroads, curves, or other influencing factors, it may be necessary to adjust the length of tapers, or extend the tangent section of the lane closure so the taper can be established in advance of these factors. Recommended minimum values for taper lengths, “L”, are shown in following table.

Table 3: Recommended Distance of Tapers at Work Areas

Velocity Taper

V < 35 mph 75 m

3.4.8. Buffer Space

Buffer Space is a feature that separates traffic flow from the work activity. No equipment, materials or vehicles shall be stored in the buffer space. Recommended minimum values for buffer lengths are shown in following table.

Table 4: Recommended Distance of Work Areas

Velocity Buffer

V < 35 mph 75 m

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3.4.9. Drum Spacing for Channelization

Spacing of channelizing devices, in feet, along the taper should not exceed the posted speed in miles per hour and twice the posted speed in the parallel area. Drums on a tangent, to keep traffic out of the closed lane, should be spaced in accordance with the extent and type of activity, the speed limit of the roadway, and the vertical and horizontal alignment of the roadway. For safety reasons it has been determined that for this project the spacing will not exceed 5.0 m (15 ft.).

3.4.10. Flashing Arrow Panels Location

For the installation of the Flashing arrows the contractor will follow the recommendations of the

Manual of Uniform Traffic Control Devices, where it is states: "For stationary lane closure, the arrow panel should be located on the shoulder at the beginning of the merging taper. Where the shoulder is narrow, the arrow panel should be located in the closed lane."

3.4.11. Portable Changeable Message Signs (PCMS)

A PCMS is primarily used to give motorists real-time traffic safety and guidance information about planned and unplanned events that significantly impact traffic on the State's highway system.

PCMS in PR-124 is going to be used as a supplement for conventional traffic control devices.

The proposed message to be displayed prior the project begins read as follows:

TRABAJOS

EN

PR-124

FECHA

DE

COMIENZO

3.5.Environmental Overview

This environmental overview identifies environmental resources and environmentally sensitive areas within the study area. The overview will be used to understand environmental constraints for the development and evaluation of improvement alternatives. Because federal funding is identified for the project, a National Environmental Policy Act (NEPA) study is required to be sure that the project complies with federal regulations. The resource investigations below would be triggered by a project sponsor receiving federal funds or a federal permit for the corridor improvements.

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3.5.1. Cultural Resources (Historic and Archeological Resources)

An Identification of Historic Properties and Assessment of Effects were conducted with the objective of identifying the presence or absence of cultural resources in the proposed action area of potential effects (APE). Project is located on a segment of PR-124 with is more than 50 years old, however it is considered not-eligible to the NRHP. There are no additional historic properties or archaeological resources reported or present within the project area or in its immediate periphery.

Proposed action would have no effect on historic properties, as there are no historic properties within the project area, and the potential of finding previously unknown archaeological resources during project activities is very low. No additional archaeological studies are recommended.

Figure 8: Historic and Archeological Resources Map

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3.5.2. Water Resources and Wetlands

The project would not impact “waters of the United States” nor wetlands areas.

Figure 9: Water Resources and Wetlands Map

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3.5.3. Threatened and Endangered Species and Wildlife Habitat

Based on the relatively developed nature of the corridor, no federal candidate, threatened, and endangered species are likely to occur within the study area. Assessments of the natural environment should be prepared in the area of the proposed action; results are summarized in the following list.

Figure 10: Threatened and Endangered Species and Wildlife Habitat Map

FLORA AND FAUNA STUDY

According to a field inspection it does appear that a minimal direct impact to mammal, birds, reptiles and amphibians is anticipated by the construction of this project. No indirect or cumulative impacts are anticipated by the construction and operation of the proposed project. The reconstruction will have a minimal impact on natural communities.

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Preliminary research shows that no endangered or critical plant and animal species habitats as defined by the Federal Endangered Species Act are present at the study site. However, a Flora and Fauna Study (FFS) have to be prepared to assess the effects of the Proposed Action on federally and locally protected biotic resources. The FFS have to follow the guidelines established by the US Fish and Wildlife Service (USFWS) and Puerto Rico Department of Natural and

Environmental Resources (PRDNER).

TREE INVENTORY AND MITIGATION PLANTING PLAN (TI-MPP)

A Tree Inventory (TI) has to be performed along the proposed action site. The inventory has to be prepared according to Puerto Rico Joint Regulation for Construction and Land Use, as amended.

The project area and TI will be used to determine potential forest areas impacts, as required by

PR Department of Environmental and Natural Resources and Puerto Rico Joint Regulation for

Construction and Land Use.

3.5.4. Floodplains

The project site is mapped as Zone X according to Federal Emergency Management Agency

Flood Insurance Rate Maps (FIRMs).

The Zone X is areas designated by the FEMA as having a moderate or minimal risk of flooding.

The study area included the following FIRM:

• Map #72000C0570H (Effective date: April 13, 2018 & reviewed in May 12, 2018.)

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Figure 11: FEMA Flood Zone Map

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3.5.5. Construction Impacts

Potential construction emissions were evaluated qualitatively. Construction emissions would be temporary and are not anticipated to cause air quality violations. Construction activities that could affect air quality include soil-disturbing activities, heavy-duty equipment exhaust, commuting workers’ motor vehicle exhaust, and asphalt paving. The total emissions and the timing of the emissions from these sources would vary depending on the phasing of the construction activities and would not all occur simultaneously. Construction-related emissions would be temporary and typically of short duration. Typical sources of emissions during construction of reconstruction projects include:

• Fugitive dust generated during excavation, grading, loading, and unloading activities;

• Dust generated during demolition of pavement;

• Engine exhaust emissions from construction vehicles, worker vehicles, and diesel fuel-fired construction equipment;

• Volatile organic compounds and odorous compounds emitted during asphalt paving; and

• Increased motor vehicle emissions associated with increased traffic congestion during construction.

Contract documents for the proposed project should require the contractor(s) to comply with all applicable air quality regulations during construction of the project.

3.5.6. Other Resources

Proposed actions do not require the acquisition of structures, and/or the relocation of families or business. The project will not cause or induce alterations in land uses, planned growth, development patterns, nor to any cultural resources, critical habitats, endangered species or parklands and would not have a significant impact in the existing environment or on nearby areas.

It’s appears that this project would not have a significant impact in the existing environmental resources.

Based on Section 771.115 (b) and 771.117 (a), (c) of the Code of Regulations (23 CFR), this project is classified as Class II Action (Categorical Exclusion). Therefore, neither an

Environmental Assessment nor an Environmental Impact Statement is required.

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4. TECHNICAL SOLUTION ALTERNATIVES

Three alternatives are presented in this technical report taking into consideration the information gathered for the project site and the preliminary geotechnical evaluation. As discussed in the previous sections, the impacts of the hurricanes were worsened by two existing characteristics of the project area:

1. The area where the landslide occurs is a low elevation point in the project segment.

2. The surface water collected by the roadside south ditch are discharging directly into base of the landslide area without any erosion protection.

Based on these two considerations, all the alternatives proposed for this project include the installation of drainage features to properly control the surface runoff at south side of the roadway and prevent future erosion of the roadway embankment slope. A Gabion Drop Structure will be constructed at the end of the existing ditch (Concrete Paved Waterway, CPW) on the south side of the PR-124 east approach.

All the alternatives proposed include the same drainage system for the project area. However, the three alternatives repair the landslide using a different retaining wall system. Based on the geotechnical recommendations, cantilever or gravity retaining wall systems are better suited for the geometry and subsurface conditions of the project site.

The reader is referred to Appendix A, where an aerial view plan with the proposed solution is presented in addition to typical sections depicting the three earth retaining alternatives.

4.1.Alternative A (New Gabion Retaining Wall)

This alternative consists in the construction of a new gabion retaining wall with a height of approximately 5.25 meters, with a foundation depth of 1.50 meters. At the top of the gabion wall, an “F” shape concrete barrier would be constructed in conjunction with a counterweight footing.

This alternative will require performing an excavation for the gabion wall foundation that would reach underneath PR-124. Therefore, this alternative will require a braced excavation to maintain one lane of the roadway open during construction considering that no short detours were found for this site.

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4.2.Alternative B (MSE Wall with Gabion Facing)

Alternative B consists in the construction of a new retaining wall using Mechanically Stabilized

Earth (MSE) with a Gabion Facing. Similarly to Alternative A, the wall would have a height of approximately 5.25 meters, with a foundation depth of 1.50 meters. At the top of the gabion wall, an “F” shape concrete barrier would be constructed in conjunction with a counterweight footing.

This retaining wall system allows the gabion face to be more inclined than a typical gabion retaining wall or even stepped. In this manner, the retaining wall can be placed in a more favorable position to suit specific soil conditions.

Similarly to Alternative A, this alternative will require performing an excavation for the retaining wall foundation that would reach underneath PR-124. Therefore, this alternative will require a braced excavation to maintain one lane of the roadway open during construction considering that no short detours were found for this site.

4.3.Alternative C (Reinforced Concrete Cantilever Wall)

Alternative C consists on the construction of a Reinforced Concrete Cantilever Wall. The Wall would have a height of 5.25 meters with a foundation depth of 1.50 meters. An “F” shape concrete barrier would be constructed at the top of the retaining wall to protect vehicles from the height difference.

This alternative will require an excavation for the base of the wall that would reach underneath

PR-124. Therefore, this alternative will require a braced excavation in order to maintain one lane of the roadway open during construction considering that no short detours were found for this site.

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5. ALTERNATIVES EVALUATION

Three alternatives have been presented in this Technical Report as possible solutions for the damage repairs of site ER-HWY-107 located in State Road PR-124, Km. 22.35. The following section presents an evaluation of the alternatives to compare their benefits and disadvantages with the objective of selecting the most efficient and cost-effective solution.

5.1.Construction Cost

A construction cost was estimated for each alternative based on the principal design elements that comprise each alternative. Table 6 presents the cost comparison of the four alternatives. A construction cost opinion for each alternative is included in Appendix E.

5.2.Constructability

The constructability of each alternative is compared in Table 6. All alternatives are relatively simple in terms of constructability. Alternative B may require more specialized materials for the construction of the MSE mass. All alternatives would require a braced excavation during construction, which could represent additional challenges during construction.

5.3.Construction Time

To determine the construction time for the ER-HWY-107 reconstruction project the Estimated

Cost Method was utilized. The Estimated Cost Method of construction time determination utilizes a comparison of dollar value to time. Based on PRHTA historical information, project cost versus time was determined. The construction time may vary according to project type such as new construction, reconstruction, overlay and widening projects, pavement repair, and bridge construction, etc.

Factors which may influence the construction time are:

1. Effects of maintenance of traffic and the sequence of operations;

2. Inclement weather conditions;

3. Curing time and waiting periods between successive paving courses;

4. Minimize annoyances in residential areas.

5. Minimize traffic disruption and delay in high traffic areas.

6. Political sensitivity and public awareness.

7. Coordination with adjoining projects to provide usable roadway sections to avoid conflicting operations.

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8. Time for reviewing RFI’s, shop drawings, mix designs, etc.

9. Coordination with utilities;

10. Time to obtain necessary permits;

11. Restrictions for weekdays, nighttime and weekend operations. And others.

Estimated construction times are shown in the alternative evaluation table.

5.4.Solution Complexity

The project location and limited access to the work area imposes limitations for construction activities. The lack of a feasible detour route for the site implies that construction works shall be completed without roadway closures. This represents a complication for the project construction of any of the alternatives. In the specific case of Alternative B, the retaining wall system is more sophisticated due to the use of Mechanically Stabilized Earth.

5.5.ROW Impact

A preliminary investigation was conducted with the objective of identifying parcels affected by the proposed actions at site ER-HWY-107. According to the research using “Catastro Digital – Centro de Recaudaciones de Ingresos Municipales” database, approximately two (2) parcels would be affected and may require partial acquisition or temporary easements. A list of the affected parcels is shown in the following table:

Table 5: Affected Parcels by the Proposed Actions

PARCEL DATA

Property Tax Number (# Catastro)

185-000-004-70 185-000-004-52

Owner Not Available Not Available

Parcel Area 126,523.75 meters 4,049.65 meters

REGISTRY DATA

Tomo N/A N/A

Folio N/A N/A

Parcel Number N/A N/A

Deed Number N/A N/A

Technical Report Page 27

Figure 12: Affected Parcels by the Proposed Actions (Source: Catastro Digital – CRIM)

5.6.Environmental Considerations

Based on the research and studies conducted on site up to this stage, no limiting impacts to the environment are expected from the project development. Based on this consideration and the fact that all alternatives have a relatively similar footprint, all alternatives are considered similar in terms of environmental considerations.

5.7. Impact on Utilities

An aerial power & telephone lines were observed in the project area, but no impacts are expected in those lines from the proposed solutions. From the research done in the Planning Board

Database, it was found that two (2) potable water lines of 2” and 16” are passing through PR-124 as shown in Figure 13. From the information obtained, it cannot be determined if the line is running through the west or east side of the roadway. At this stage, it is considered that all alternatives have the potential of impacting those lines for construction. To minimize service disruption, it is recommended to protect the existing pipe in place during construction.

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Figure 13: Water Utilities in Project Site

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Table 6: Comparison of Alternatives for ER-HWY-107

Comparison Element ALTERNATIVE A ALTERNATIVE B ALTERNATIVE C

Construction Cost $238,971 $269,222 $325,452

Constructability

Normal roadway construction methods and equipment required.

Normal roadway construction methods and equipment required.

Normal roadway construction methods and equipment required.

Construction Time 4.8 months 5.4 months 6 months

Solution Complexity Above normal but not complicated

Above normal but not complicated

Above normal but not complicated

ROW Impact

Minimal ROW Acquisition may be required.

Construction Easements may be required.

Minimal ROW Acquisition may be required.

Construction Easements may be required.

Minimal ROW Acquisition may be required.

Construction Easements may be required.

Flora

No special or protected flora is seen in the area of the project.

No special or protected flora is seen in the area of the project.

No special or protected flora is seen in the area of the project.

Fauna

No protected species are detected in the area of the project.

No protected species are detected in the area of the project.

No protected species are detected in the area of the project.

Impacts to Waters of the USA

No temporary and/or permanent impacts expected.

No temporary and/or permanent impacts expected.

No temporary and/or permanent impacts expected.

Archeological

Resources

No additional archeological studies are recommended.

No additional archeological studies are recommended.

No additional archeological studies are recommended.

Technical Report Page 30

Comparison Element ALTERNATIVE A ALTERNATIVE B ALTERNATIVE C

Impact on Utilities

16” and 2” Water Lines may be affected. Information about underground utilities will be requested to the agencies.

16” and 2” Water Lines may be affected. Information about underground utilities will be requested to the agencies.

16” and 2” Water Lines may be affected. Information about underground utilities will be requested to the agencies.

Traffic Impact

NB Lane Closure required during construction duration.

No short detours were found for the site.

NB Lane Closure required during construction duration.

No short detours were found for the site.

NB Lane Closure required during construction duration. No short detours were found for the site.

Effectiveness of problem Solution

Landslide damages will be corrected. Drainage deficiencies will be eliminated.

Landslide damages will be corrected. Drainage deficiencies will be eliminated.

Landslide damages will be corrected. Drainage deficiencies will be eliminated.

Technical Report Page 31

6. RECOMMENDATIONS

Observing the conditions of the project site, it is our understanding that the proper collection of runoff water in the project area is a critical factor for designing a permanent solution that will be resilient to future atmospheric events such as Hurricanes Irma and María. Based on this presumption, it is of great importance that a properly designed drainage system is constructed in the area to protect the landslide repair.

The presence of hard soils in the project site limits the available options for retaining walls that could minimize the traffic impacts such as a soldier pile wall, drilled shafts, amongst others. Based on this consideration, three different alternatives for the construction of a retaining wall were presented. The three alternatives are relatively simple in terms of complexity and constructability. All alternatives will require a braced excavation in order to keep the southbound lane open during the construction of the retaining wall foundation.

Considering that all alternatives will have relatively similar impacts to the traffic in the area, the final recommendation for the project will be based on the cost, construction time and durability of the alternative. The reinforced concrete wall, Alternative C, represents the alternative with the higher cost of construction and construction time. When Alternative C is compared with the other two alternatives in terms of durability, there is no definitive advantage that justifies the extra cost of Alternative C. When compared to Alternative A, Alternative B has a higher construction cost and requires slightly more sophisticated construction methods due to the use of Mechanically Stabilized Earth. Based on the previous, our recommended alternative is Alternative A since it represents the more cost-effective solution to the landslide correction at this site.

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APPENDIX A: PLANS FOR TECHNICAL

SOLUTION ALTERNATIVES

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APPENDIX B: SURVEY PLANS FOR PROJECT SITE

Technical Report Page 37

APPENDIX C: PRELIMINARY ENVIRONMENTAL

EVALUATION TECHNICAL MEMORANDUM

Landslide and Road Damage Evaluations and Repair Recommendations ER-HWY-107, PR-124 km 22.35, Lares, P.R

1 Torres-Rosa Consulting Engineers

ER-HWY-107_TM_20190212

Preliminary Environmental Evaluation Technical Memorandum

To: Eng. Herminio Alamo Barret Hale & Alamo, LLC h.alamo@bha-llc.com

From: Eng. Rafael Rosa-Castro

Torres-Rosa Consulting Engineers rrosa@trcepr.com

Re: ER-HWY-107

Date: February 12, 2019

The Puerto Rico Highway and Transportation Authority (PRHTA) and the Federal Highway Administration

(FHWA) propose the reparation of road damage located at km. 22.35 of PR-124 in the municipality of

Lares, Puerto Rico. Road damages are due to the impacts associated with Hurricanes Irma and María.

Figure 1 and Figure 2 show proposed action location at USGS Topographic Map and Aerial Photo, respectively. This document summarizes the preliminary environmental findings and environmental determinations of the proposed action. The findings are based on government agencies information and studies conducted in the area of the proposed action; the studies are included in the Attachment A.

Preliminary environmental determinations are based on environmental findings and conversations with the design team.

Figure 1 Proposed Action Location in USGS Quadrangle.

mailto:h.alamo@bha-llc.com mailto:rrosa@trcepr.com

2 Torres-Rosa Consulting Engineers

Figure 2. Proposed Action Location in Aerial Photo (source BH&A).

Natural Environment

The natural environment in the area where the proposed action is located was evaluated using information published by government agencies and field visit. The following studies are recommended.

1. Flora and Fauna Study - A Flora and Fauna Study (FFS) should be prepared to assess the effects of the Proposed Action on federally and locally protected biotic resources.

2. Tree Inventory and Mitigation Planting Plan (TI-MPP) - The Hurricane María occurred on September

20, 2017 and there are trees in the area where the proposed action is located. The potential impact on the existing trees will be used to determine the impacts and mitigation measures of

Recommended Alternative.

Cultural Resources

An Identification of Historic Properties and Assessment of Effects were conducted with the objective of identifying the presence or absence of cultural resources in the proposed action area of potential effects

(APE). Project is located on a segment of PR-124 with is more than 50 years old, however it is considered not-eligible to the NRHP. There are no additional historic properties or archaeological resources reported or present within the project area or in its immediate periphery.

Proposed action would have no effect on historic properties, as there are no historic properties within the project area, and the potential of finding previously unknown archaeological resources during project activities is very low. No additional archaeological studies are recommended.

3 Torres-Rosa Consulting Engineers

Environmental Class of Action Determination

Based on available information Proposed Action can be classified as a Class Action Type II according to

23 Code of Federal Regulations (CFR), Section 771.115(b).

Torres-Rosa Consulting Engineers

Attachment A Cultural Assessment

Landslide and Road Damage Evaluation and Repair

Identification of Historic Properties and Assessment of Effects / Section 106 Review Process PR-124 / Km 22.35/ Lares [ER-HWY-107]

Prepared for:

Puerto Rico Highway and Transportation Authority

Environmental Studies Office and

Puerto Rico State Historic Preservation Office

Sharon Meléndez Ortiz February 8, 2019

Landslides and Road Damage Evaluation Repair, Identification of Historic Properties and Evaluation of Effects

PR- 124, km 22.35, Lares [ER-HWY-107]

Preamble

The Puerto Rico Highway and Transportation Authority (PRHTA) is evaluating the repair of approximately 700 landslides on several highway segments of Puerto Rico due to the impacts associated with Hurricanes Irma and María. These highway and road segments are either within the Puerto Rico’s Federal Aid Highway System, or under the jurisdiction of the Department of Transportation and Public Works. The reconstruction activities will be financed by Emergency Funds from the Federal Highway Administration (FHWA).

Section 106 of the National Historic Preservation Act (NHPA) requires that all federal agencies take into account the potential effects of their proposed projects on historic properties. This form has the objective of facilitating, streamlining and expediting the FHWA’s compliance under the law, and the Puerto Rico State Historic Preservation Office (PRSHPO) review process for these projects.

Landslides and Road Damage Evaluation Repair, Identification of Historic Properties and Evaluation of Effects

I. Project General Information I.1. Project name: Landslide and Road Damage Evaluation and Repair

I.2. State Project no.: ER-HWY-107

I.3. Federal Project no.: ER-HWY-107

I.4. Road: PR-124

I.5. KM: 22.35

I.6. Municipality: Lares

I.7. Coordinates: LAT/LONG 18.268672°, -66.899114°

NAD 83 Northing 248,246.414 Easting 150,747.091

I.8 Proposed construction activities Describe the proposed construction activities. Include staging areas and new access roads, if any.

Landslides and Road Damage Evaluation Repair, Identification of Historic Properties and Evaluation of Effects

II. Cultural Resources1. Desk Review.

For purposes of this form, the project’s area of potential effects (APE) corresponds to the project area.

II.1. Are there any known archaeological sites within or adjacent to the project area?

_X_ No. ___Yes. Complete Table 1.

II.2. Are there any known buildings, structures or objects within the project area?

II.3. Is the project located within a known historic district or adjacent to one?

II.4. Is the segment of the road where the project is located 50 years or older?

___ No. _X_ Yes. Include in Table 1.

II.5. Are there any prior cultural resources surveys conducted within the project area or that include the project area?

___ No. Continue to section III. _X_ Yes. Complete Table 2 and continue to II.6.

II.6. Were cultural resources identified in a prior cultural resources survey?

_X_ No. Continue to section III. ___Yes. Include resource in Table 1.

1 For definitions and examples of concepts (site, buildings, structures, objects) refer to the National Register Bulletin How to Apply the National Register Criteria for Evaluation https://www.nps.gov/nr/publications/bulletins/nrb15/nrb15_4.htm.

https://www.nps.gov/nr/publications/bulletins/nrb15/nrb15_4.htm

Landslides and Road Damage Evaluation Repair, Identification of Historic Properties and Evaluation of Effects

III. Site Visit

III.1. Name of archaeologist who conducted the site visit and date(s) of the visit:

Sharon Meléndez Ortiz. January 19, 2019

III.2. Is there a bridge, culvert, or other drainage structures in the project area?

_X_ No. Continue to III.4. ___ Yes. Continue to III.3.

III.3. Is the structure 50 years or older?

__ No. Continue to III.4. ___ Yes. Include in Table 1 and continue to III.4.

III.4. During the site visit, were previously unknown sites, buildings, structures or objects identified within or adjacent to the project area?

_X_ No. Continue to III.6. ___ Yes. Continue to III.5.

III.5. Is the site, building, structure or object that was identified during the site visit 50 years…