Technical Report - AC-919579_HWY-259.pdf

PROFESSIONAL SERVICES CONTRACT FOR PROJECT:

LANDSLIDE AND ROAD DAMAGE

EVALUATION AND REPAIR RECOMMENDATIONS

TECHNICAL REPORT

Design Criteria – Engineering Technical Report

For the Site:

ER-HWY- 259 at PR-155 Km. 38.35

Municipality of Morovis, PR

Prepared for:

DEPARTMENT OF TRANSPORTATION AND

PUBLIC WORKS

PUERTO RICO HIGHWAY AND TRANSPORTATION AUTHORITY

Prepared by:

UNIPRO

Architects - Engineers LLP

Amelia Industrial Park 4 Amelia St. Guaynabo, PR 00968-8003

Contract No.: 2019-000129

AC-816544/ER-9999-325

RPE1699544

PRHTA Design Area

JANUARY 7, 2019

Revised February 18, 2019

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UNIPRO Technical Report (AC-816544)

Landslide and Road Damage Evaluation ER-HWY-259, PR-155, Km. 38.35

Revised February 18, 2019

Contents

1.0 EXECUTIVE SUMMARY

2.0 PROJECT DESCRIPTION

3.0 EXISTING CONDITIONS

3.1 Existing Roadway Characteristics

3.1.1 Functional Classification

3.1.2 Typical Section and Right-of-Way

3.1.3 Utilities and Drainage

4.0 DESIGN CRITERIA FOR ROADWAY

4.1 TRAFFIC VOLUMES

4.2 DESIGN ELEMENTS

4.3 DESIGN SPEEDS

4.4 HORIZONTAL ALIGNMENTS

4.5 VERTICAL ALIGNMENTS

4.6 LANE WIDTHS

4.7 DESIGN VEHICLE

4.8 ROADWAY ELEMENTS

4.9 ROADSIDE DESIGN

4.10 PAVEMENT DESIGN

4.11 PAVEMENT MARKING AND SIGNING

4.12 DRAINAGE

4.13 HYDROLOGIC / HYDRAULIC ANALYSIS

4.14 CURBS and BARRIERS

4.15 CLEARING AND GRUBBING

4.16 RIGHT OF WAY

4.17 ACCESS

4.18 PEDESTRIAN MOVEMENTS

4.19 CLEARANCES

4.20 LIGHTING

5.0 DESIGN CRITERIA FOR STRUCTURES

ER-HWY-259, PR-155, Km. 38.35

5.1 CAST IN PLACE STRUCTURES

5.1.1 Construction Specifications:

5.1.2 Design Specifications:

5.1.3 Dead Loads:

5.1.4 Design Method:

5.1.5 Reinforcing Steel:

5.1.6 Foundations:

5.1.7 Concrete Cover:

5.1.8 Chamfers:

5.1.9 Epoxy Compounds:

5.1.10 Temporary Retaining Structure:

5.1.11 Construction Joints in Concrete:

6.0 ENGINEERING ASSESSMENT

6.1 HORIZONTAL ALIGNMENT ALTERNATIVE ANALYSIS

6.2 Roadway Design

6.3 Transit

6.4 Critical Issues (Problems and Solutions)

6.5 Construction Drawings and Technical Specifications

6.5.1 Temporary Utility Relocation’s

7.0 ENVIRONMENTAL STUDIES

7.1 Environmental Characteristics

7.1.1 Ecological Assessment

7.1.2 Survey for Asbestos Containing Material (ACM) and an Environmental Survey for Lead Based Painted (LBP)

7.1.3 Cultural Resources Assessment Phase I

Table No. 7.1 Environmental Findings Summary

8.0 GEOTECHNICAL INVESTIGATION

8.1 GEOLOGY AND SUBSOIL CONDITIONS

8.2 ANALYSIS, CONCLUSIONS AND RECOMMENDATIONS

8.2.1 Gravity Retaining Wall

8.2.2 Reinforced Concrete Retaining Wall

8.2.3. Mechanically Stabilized Earth Wall

8.4 Earthwork Recommendations

ER-HWY-259, PR-155, Km. 38.35

9.0 RETAINING WALL ALTERNATIVES ANALYSIS AND RECOMENDATIONS . 28

Table No. 9.1 Retaining Wall Alternatives Analysis

Table No. 9.2 Retaining Wall Alternatives Cost Summary

Table No. 9.3 Retaining Wall Alternatives Rating Matrix (RWARM)

9.1 Retaining Wall Recommendations

Table No. 9.4 Retaining Wall Recommendations Summary

ATTACHMENTS

PHOTOS OF THE LANDSLIDE AREA

DDIR PREPARED BY THE PRHTA

GEOTECHNICAL INVESTIGATION

PRELIMINARY ENVIRONMENTAL FINDINGS

CULTURAL RESOURCES ASSESSMENT

SURVEY TO DETERMINE THE PRESENCE OF ASBESTOS AND LEAD

FIELD SURVEY

Recommended Alternative - Conceptual Drawings

ER-HWY-259, PR-155, Km. 38.35

1.0 EXECUTIVE SUMMARY

The objective of this Engineering Report is to document the findings of the engineering assessment and to provide a summary of certain elements of the environmental and traffic evaluation for the proposed retaining walls for landslide stabilization at the site ER-HWY-259, PR-155, Km. 38.35, Pesas Ward, Municipality of Morovis. These proposed improvements are necessary to re-accommodate the traffic and to return the roadways to the original conditions.

The engineering assessments of the retaining wall alternatives are included in this report, such as: the environmental screening, traffic analysis, preliminary engineering, drainage and the design criteria for the roadway cross section options. In addition, an alternatives evaluation table and a Retaining Wall Alternatives Rating Matrix (RWARM) were also prepared. From the evaluation tables of the retaining walls alternatives, an alternative will be selected for which final construction drawings will be prepared.

Evaluation Categories- All Alternatives

Geotechnical constraints Earthwork movement, unclassified excavation for structures Environmental issues Traffic constrains Utilities Conflicts Right-of-way acquisition areas and social impacts Physical environmental impacts Conceptual Cost Estimate Timeliness Network flexibility; and Route performance and safety Drainage

Based on the existing condition (damage caused by the hurricanes), at least three alternatives are analyzed based on the evaluation categories shown above.

Each of these alternatives is discussed in detail in section 8 and 9 of this report.

2.0 PROJECT DESCRIPTION

Because of the passage of Hurricanes Irma and Maria over Puerto Rico during September 2017, quite a few of Puerto Rico’s highways, primary and secondary roads suffered significant landslides. As a result, the Puerto Rico Highway and Transportation Authority (PRHTA) was charged with the responsibility of executing the Emergency Relief Program. The PRHTA requested technical and

ER-HWY-259, PR-155, Km. 38.35 financial proposals from qualified engineering consultants, to provide support in their Emergency Relief Program. UNIPRO as part of the selected firms is tasked with the preparation of the Construction Drawings, Specifications and Cost Estimate (PS&E) for the remediation of the landslide.

The project consists of the evaluation and design for the reconstruction of roads affected by landslides; i.e., slope instability, washouts and rock fall on several highway segments (see site location details below) due to the impacts associated with Hurricanes Irma and María. Those highway segments are located within the Puerto Rico’s Federal Aid Highway System, and other highways and roads under the Department of Transportation and Public Works (DTPW) jurisdiction.

UNIPRO is performing the site reconnaissance, investigations, monitoring and studies, necessary to provide appropriate recommendations to reconstruct the highway to its previous condition, to provide traffic safety, functionality, and operations on the roadways segments assigned.

Project ID # Highway Kilometer Municipality PS&E Group

ER-HWY- 258 PR-155 37.00 Morovis A

ER-HWY- 259 PR-155 38.35 Morovis A

ER-HWY- 260 PR-155 39.10 Morovis A

ER-HWY- 261 PR-155 40.30 Morovis A

ER-HWY- 262 PR-155 43.00 Morovis A

ER-HWY- 263 PR-155 43.25 Morovis A

ER-HWY- 265 PR-155 56.70 Morovis A

ER-HWY- 267 PR-155 30.10, 30.2 Orocovis B

ER-HWY- 270 PR-156 3.60 Orocovis B

ER-HWY- 271 PR-156 4.40 Orocovis B

ER-HWY- 273 PR-156 6.30 @ 6.40 Orocovis B

ER-HWY- 274 PR-156 17.80 Barranquitas C

ER-HWY- 275 PR-156 3.70, 3.80 Orocovis B

ER-HWY- 276 PR-156 18.00 Barranquitas C

ER-HWY- 299 PR-172 24.80 Caguas C

ER-HWY- 302 PR-173 28.40 Guaynabo C

ER-HWY- 303 PR-173 31.20 Guaynabo C

ER-HWY- 306 PR-173 10.30 Cidra C

ER-HWY- 307 PR-175 12.10 Trujillo Alto C

For the evaluation of the alternatives, the horizontal and vertical alignments shall be as simple as possible to facilitate the construction of the project, to lower construction costs and avoid problems during the construction stage. Whenever possible, the project shall be designed with the least possible interruptions to traffic.

Highway improvements shall comply with existing codes, regulations, standards and directives (except as specified herein). The proposed design shall comply with FHWA’s Emergency Relief Program, defined under 23 CFR 668, Parts A and B. Procedures shall meet FHWA’s Emergency Relief Manual (Federal-Aid Highways) 2009. If betterments are proposed, these shall be justified and follow

ER-HWY-259, PR-155, Km. 38.35

ER Manual requirements.

The project design shall comply with the PRHTA’s Highway Design Manual (HDM), the most recent AASHTO’s manuals, including the Roadside Design Guide, the PRHTA’s Standard Specifications for Road and Bridge Construction, 2005; and amendments; with supplementary specifications, with PRHTA’s latest Standard Models and Design Directives, and with any other manual that applies.

ER-HWY-259, PR-155, Km. 38.35

ER-HWY-259, PR-155, Km. 38.35

3.0 EXISTING CONDITIONS

ER-HWY-259, PR-155, Km. 38.35, Pesas Ward, Municipality of Morovis

3.1 Existing Roadway Characteristics

3.1.1 Functional Classification

The State Road PR-155 is part of the secondary road network of Puerto Rico; it is considered a rural two lane collector roadway with variable shoulder at both sides. PR-155 connects the municipalities of Morovis and Orocovis. The roadway runs north – south from the State Road PR-633 to State Road PR-156 at the Municipality of Orocovis.

3.1.2 Typical Section and Right-of-Way

Based on the document ―Guia Para Las Secciones Típicas de Las Carreteras del Estado Libre Asociado de Puerto Rico, Departamento de Transportación y Obras Públicas y la Autoridad de Carreteras y Transportación revisado al 31 de octubre de 1991‖, the State Road PR-155 at Km. 38.35 has a section of 15.00 Mts. of Right-of-Way with a roadway section of 6.00 mts. plus shoulder, verified by the Field Survey performed by Javier E. Bidot Associates, PSC Land Surveyor & Consultants on November 21, 2018 (see attachment).

3.1.3 Utilities and Drainage

In addition to serving vehicular traffic, pedestrians, and other users, the road right-of-way also accommodates a variety of underground and aboveground utilities, which are owned by private and public entities. Since the horizontal and vertical locations of these utilities must be coordinated with the road improvements during the design and construction, it is important to identify these existing and proposed utilities in the early stages of the project development.

ER-HWY-259, PR-155, Km. 38.35

ER-HWY-259, PR-155, Km. 38.35

4.0 DESIGN CRITERIA FOR ROADWAY

The following criteria is based on the PRHTA Highway Design Manual, 1979, and on AASHTO’s ―A Policy on Geometric Design of Highways and Streets‖, 2011 (6th edition) (AASHTO Green Book), AASHTO’sRoadsideDesignGuide2011 (4th edition),PRHTA Standard Specifications for Road and Bridge Construction, 2005, PRHTA Standard Drawings, Design Area, Design Directives, ―Guías de Secciones Típicas para las Carreteras del Estado Libre Asociado de Puerto Rico, 1991‖ Universe Sample Data of the Puerto Rico Highway and Transportation Authority and is intended to provide standardization of roadway and bridge design procedures. The more stringent requirement of these manuals will be used in the design of the project.

4.1 TRAFFIC VOLUMES

Traffic volume for PR-155: 9,200 for 2016 year. K D T

Upcoming: 12,600for 2034 year. 8% 60% 3.20%

4.2 DESIGN ELEMENTS

General Roadway Design

The design elements according to the volumes are as follows: (Table 1-12 of

HDM):

PR-155 R-5*

* Note: R-6 was used for this project due to existing site conditions and restrictions.

4.3 DESIGN SPEEDS

The design speed shall be as follows:

PR-155 (Mountain) 40 KPH

4.4 HORIZONTAL ALIGNMENTS

Radio of the horizontal curve is as follows: 140 mts.

Used at Project

PR-155 Used at Project Minimum 140mts.

At intersection N/A

4.5 VERTICAL ALIGNMENTS

As a Grades in percent (%) shall be as follows:

Used at Project Maximum Percent 8 Approach Road Match Existing

Minimum grades Minimum 0.5

Table No. 4.1 Design Control for Crest Vertical Curve Based on Stopping Sight Distance.

Design Speed Stopping Sight Rate of Vertical Curvature, Ka (km/h) Distance (mts.) Calculate Design

40 50 3.8 4

Table No. 4.2 Design Control for Crest Vertical Curve Based on Passing Sight Distance.

Design Speed Passing Sight Rate of Vertical Curvature, Ka (km/h) Distance (mts.) Design

40 140 23

Table No. 4.3 Design Control for Sag Vertical Curve.

Design Speed Stopping Sight Rate of Vertical Curvature, Ka (km/h) Distance (mts.) Calculate Design

40 50 8.5 9

Crest and sag vertical curves tables 2 to 4 was developed based on the desirable length determined from Tables 3-34 to 3-36, of AASTHO.

4.6 LANE WIDTHS

PR-155 3.60mts.

Approach Road: Match Existing

4.7 DESIGN VEHICLE

The design of this project shall provide for the operation of WB-50.

4.8 ROADWAY ELEMENTS

SHOULDERS: Shoulders of 2.40 mts. is proposed to be used through all the proposed area of the project only, and in the roadway to match existing.

4.9 ROADSIDE DESIGN

Chapter 8 of the PRHTA Design Manual, Standard Drawings of PRHTA and the 2011 AASHTO Roadside Design Guide will be used to design the roadside for the project. Guard Rails will be used in the PR-155 to match to existing, concrete barrier at the base of retaining walls structures shall be considered.

Side slopes of 4:1 H:V will be used up to 3.0 meters of embankment height. Side slopes of 2:1 H:V will be used for embankment height higher than 3.0 meters.

Ditches in accordance with AASHTO Roadside Design Guide will be used.

Bridge parapets, traffic barriers and traffic barriers transitions and terminals will be designed in accordance with the PRHTA MB Standard Drawings.

Riprap will be recommended to minimize the erosion.

4.10 PAVEMENT DESIGN

Asphalt pavement, according to the PRHTA Design Directives Number 210, will be used. Design will be based on the AASHTO Soils Classification System and traffic volumes and type of traffic.

4.11 PAVEMENT MARKING AND SIGNING

Pavement marking and signing will be done in accordance with the DTPW ―Manual de Señales de Tránsito para las Vías Públicas de Puerto Rico‖, the PRHTA Standard Drawings, and the FHWA Manual of Uniform Traffic Control

Devices for Streets and Highways (2009 editions or latest). Reflective thermoplastic pavement marking material will be used. Break-away signs will be used.

4.12 DRAINAGE

The minimum diameter of circular culverts crossing the highway will be determined by the length as defined in Item 11-04-02 of the HDM, or as directed by any additional governing regulations. The minimum pipe diameter for closed systems shall be 18‖.

4.12.1 Swales and Ditches: Those designed to convey runoff adjacent to the proposed roadway will be sized to handle the 25-year peak runoff rate.

4.12.2 Ditches: Those receiving runoff from proposed cross drains, will be analyzed based upon the 25-year storm event. The 100-year storm event will also be evaluated.

4.13 HYDROLOGIC / HYDRAULIC ANALYSIS

For the site studied and presented in this report (ER-HWY-259at PR-155 km.

38.35) no hydrologic-hydraulic study was considered necessary.

4.14 CURBS and BARRIERS

Curbs and barriers will be constructed wherever it is necessary to prevent vehicles from running off the road, and to provide the proper transition from the rehabilitation project to existing road section.

4.15 CLEARING AND GRUBBING

Provisions will be made in the project so that the contractor shall clear, grub, remove and dispose of all vegetation, debris and miscellaneous demolition of the structures to be demolished and removed, within the Right of Way (R.O.W.) limits as directed by the Engineer. All trees within the R.O.W. will be surveyed and a reforestation plan will be implemented if needed.

4.16 RIGHT OF WAY

The project will be designed over the existing roadway and no additional R.O.W.

are expected to be acquired for this project.

4.17 ACCESS

Access will be permitted to the roadway.

4.18 PEDESTRIAN MOVEMENTS

The need for sidewalks will be determined based on whether they existed before the occurrence of the aforementioned rain events.

4.19 CLEARANCES

Lateral clearance from the edge of traffic lanes to vertical elements (light poles, sign support, utility poles, etc.) more than 0.3 min. height will be based on the concept of variable clear zones. Where barriers are warranted the vertical elements behind the barriers need not be fitted with breakaway bases. Where necessary to mount vertical elements within the clear zone with non-critical slopes the elements will be fitted with a breakaway base or be protected (isolated) by a suitable barrier.

Guardrails installed along the face of an obstacle or obstruction that is not breakaway should have a clearance appropriate to the dynamic lateral deflection of the particular rail type or strong post spacing.

Guardrails attached flush with the exposed faces or piers, abutments, or parapets should be stiffened preceding the obstruction to avoid snagging an errant vehicle, according to the PRHTA Standard Drawings.

4.20 LIGHTING

The need of lighting system is not foreseen.

5.0 DESIGN CRITERIA FOR STRUCTURES

5.1 CAST IN PLACE STRUCTURES

5.1.1 Construction Specifications:

Department of Transportation and Public Works (DTPW) Standard Specifications for Road and Bridge Construction, 2005 edition and supplements thereto will be used.

5.1.2 Design Specifications:

AASHTO LRFD Bridge Design Specifications, 2017, 8th Edition, and Supplements Thereto.

Guide Specifications for LRFD Seismic Bridge Design AASHTO / AWS D1.5M / D1.5:2015 Bridge Welding Code, 7th edition, 2018 AASHTO Interim.

AWS D1.4 2018 Structural Welding Code — Steel Reinforcing Bars.

HDM, DTPW Latest edition and DTPW Standard drawings.

5.1.3 Dead Loads:

DESIGN LOADING:

Unit weight of reinforced concrete (including reinforcement): ..........150 pcf Future wearing surface allowance:

applied over projected plan area of the exposed bridge deck ........... 25 psf Concrete barrier type F modified ……………………………………….400 plf

LIVE LOADS:

HL-93

WIND LOADS:

Wind loads are in accordance with ASCE 7-16, IBC 2018, and PR Building Code 2018.

EARTHQUAKE LOADS

Provisions for earthquake are in accordance with ASCE 7-16, IBC 2018, and PR Building Code 2018. Seismic acceleration coefficient (A) = 0.20.

Analysis procedure is based on the following:

Multi—mode spectral analysis method

5.1.4 Design Method:

Service load design method for all elements is used, except that strength design is used where seismic considerations govern.

Pre stressed beams are designed per the service load design method and checked per the strength design method.

Materials:

Class IV F'c = 4,000 psi structural concrete (specification 934) Class VI F'c= 6,000 psi (pre stressed beams structural conc.) Specification 934 Class VI F'ci= 5,000 psi (pre stressed beams structural conc.) Specification 934 F’c = unit ultimate compressive strength of concrete as determined by cylinder test at the age of 28 days.

F'ci = required compressive strength of concrete at time of transfer.

5.1.5 Reinforcing Steel:

All reinforcing steel shall conform to ASTM A615, grade 60. Allowable tensile stress for grade 60 is 24,000 psi where "design method" indicates service load design method. Reinforcing to be welded shall meet the requirements of ASTM A706-13: 6.2. The chemical composition as shown by heat analysis shall be limit by the following:

Element Carbon max 0.30 %.

All dimensions pertaining to location of reinforcement are to centerline of bars except where the clear dimension is shown to face of concrete or other surface.

Reinforcement splice length shall be as follows unless otherwise noted:

Bar size Splice length Splice length

(Staggered) (not staggered)

# 4 10‖ 13‖ # 5 15‖ 20" # 6 22" 28" # 7 30" 39‖ #8 40‖ 51‖ # 9 50" 55‖ # 10 64" 82" # 11 73‖ 101‖

5.1.6 Foundations:

Foundations have been designed following the recommendations stated in the soils report prepared by "GeoCim" (Luis O. Garcia Associates).

Contractor is responsible for obtaining a copy of the report and construction addenda and for following all the recommendations stated therein. These reports are part of the specifications and contract documents of the project

5.1.7 Concrete Cover:

Unless noted otherwise, concrete cover shall conform to the following:

Superstructure (cast-ln-place):

Barriers 0.05 Deck slab, top reinforced steel 0.064 Bottom reinforced steel 0.025

Substructure (cast-in-place):

Surfaces exposed to earth, formed 0.08 Surfaces not exposed to earth, formed 0.05 Cast against earth or in water drilled shaft 0.10

5.1.8 Chamfers:

All exposed edges and corners of concrete members shall be chamfered in accordance with The PRHTA Standard Specifications and as shown on design drawings.

5.1.9 Epoxy Compounds:

Epoxy compounds used for installing reinforcing steel and anchor bolts into hardened or existing concrete maybe either capsule, cartridge or pourable type. These adhesives will be approved on the basis of satisfactory performance contained in the field test reports provided by the manufacturer.

The manufacturer of the epoxy compound shall certify that the product supplied meets the above requirements. The manufacturer shall additionally certify that he has examined the particular application and that his product is recommended for the stated use for this project. The bars or anchor bolts shall be installed in strict accordance with the manufacturer’s requirements.

Epoxy materials which have been in storage for more than 12 months will not be accepted for use.

5.1.10 Temporary Retaining Structure:

The cost of any temporary retaining structure required for the construction of the retaining walls shall be included in the contract unit price for unclassified excavation structures. The contractor shall submit shop drawings of such structure for approval

5.1.11 Construction Joints in Concrete:

Construction joints will be permitted only at locations indicated on plans.

Additional construction joints or alterations to those shown shall require written approval of the engineer. All shear keys shown on the plans shall be formed. Construction joints shall be in accordance with specifications 601-3.11.

6.0 ENGINEERING ASSESSMENT

6.1 HORIZONTAL ALIGNMENT ALTERNATIVE ANALYSIS

As requested in the RFP document for the evaluation of the alternatives, the horizontal and vertical alignments shall be as simple as possible, to facilitate the construction of the project, to lower construction costs and avoid problems during the construction stage. Whenever possible, the project shall be designed with the least interruptions to traffic possible.

Highway improvements shall comply with existing codes, regulations, standards and directives (except as specified herein). The proposed design shall comply with FHWA’s Emergency Relief Program, defined under 23 CFR 668, Parts A and B. Procedures shall meet FHWA’s Emergency Relief Manual (Federal-Aid Highways) 2009. If betterments are proposed, these shall be justified and follow ER Manual requirements.

The Project design shall comply with the PRHTA’s HDM, the most recent AASHTO’s manuals, including the Roadside Design Guide, the PRHTA’s Standard Specifications for Road and Bridge Construction, 2005; and amendments; with supplementary specifications, with PRHTA’s latest Standard Models and Design Directives, and with any other manual that applies. The more stringent requirement of these manuals will be used in the design of the project.

In order to minimize the acquisition of the R.O.W. the proposed alternative recommended and approach roadway shall be designed over the path of the existing roadway.

6.2 Roadway Design

The project shall be designed maintaining the same number of existing lanes prior to the hurricane María rainfall event and the traffic shall never be interrupted during construction.

6.3 Transit

Transit maintenance plans will be prepared for all phases of construction. They will include the following:

At least maintain the same number of existing lanes in each direction on PR-155, open to transit at all times during construction.

Schedule construction phases with their correspondent signing and traffic control devices (for example: for the relocation of utilities, ramp construction, etc.), in order to avoid transit inconveniences and to maintain access.

Signing and pavement markings will also be provided.

The Maintenance of Traffic (MOT) shall comply with the DTPW Work Zone and Mobility Policy.

If the project area requires it, a Transportation Management Plan (TMP) it will be prepared prior to the preparation of the MOT.

If the selected design alternative shall be over the existing roadway the project also includes the design of a temporary detour road for the maintenance of traffic during the project construction. Riprap will be recommended to minimize the erosion.

6.4 Critical Issues (Problems and Solutions)

Based on the conceptual information obtained, we have identified what we believe are the most significant issues that may arise and which we will address in order to successfully complete the project. The major problems are the following:

Rock Excavation Maintenance of Traffic Environmental impacts Flooding

The environmental and socio-cultural issues must be managed as a critical issue to mitigate the possible impact of the project on the environment and surrounding areas.

UNIPRO has wide experience dealing with these issues and we will address them during design of the project. We will prepare a construction Maintenance of Traffic program and will take into account these and other environmental issues.

6.5 Construction Drawings and Technical Specifications

Based on the information developed in the previous tasks, and after the approval of this Engineering Report, UNIPRO will prepare contract documents consisting of Construction Drawings, Technical Specification and Cost Estimate, illustrating the engineering and design features of the proposed alternative for the remediation of the damaged roadways.

6.5.1 Temporary Utility Relocation’s

All costs for work and material required for temporary relocation of any existing utilities indicated in the drawings, shall be considered as subsidiary obligation to be assumed by the contractor, and as such costs for the construction and removal of these temporary works shall be included in the bid price for the relocation of said utilities specified in the drawings, contract documents or as ordered by the engineer

7.0 ENVIRONMENTAL STUDIES

The following paragraphs and tables show the preliminary and final findings of the environmental studies; Preliminary Biological Assessment, Habitat Categorization for Department of Natural and Environmental Resources(DNER) and Tree Inventory and Mitigations planting plan, and the final Recommendation of the Cultural Resources Assessment Phase I and Survey to Determine the Presence of Asbestos and Lead studies, and their possible impacts on the project classified as low, moderate or high impact, and recommendations for mitigations of the impacts.

7.1 Environmental Characteristics

7.1.1 Ecological Assessment

The Ecological Assessment prepared by Coll Rivera Environmental included an on-site field investigation as well as a review of published data containing information about topography, soils, vegetation, and wildlife.

The purpose of this assessment was to determine the presence of ecological conditions that could pose constraints to the proposed project.

The scope of the ecological assessment was limited to Biological Assessment, Tree Inventory, and Habitat Categorization. A brief summary of the findings is revealed below. For a copy of the Assessment Report, please refer to the Technical Appendix binder.

7.1.2 Survey for Asbestos Containing Material (ACM) and an

Environmental Survey for Lead Based Painted (LBP)

On November 12-2018, Mr. Carlos Osorio, Best Environmental Consultants Inc., performed a survey for Asbestos Containing Material (ACM) and an Environmental Survey for Lead Based Painted (LBP)at State Road PR-155, km. 38.35, at Morovis, PR. The scope of the survey included sampling and physical assessments of Suspect Asbestos Containing Materials (SACM) from the specific site where the sliding occurred to identify materials that contain asbestos fiber above allowable levels that could result in harm to construction personnel an workers and identify lead base paint coating on the sliding area. For a copy of the survey, please refer to the Technical Appendix binder.

7.1.3 Cultural Resources Assessment Phase I

For all projects that involve excavation, construction and reconstruction an Archaeological Assessment needs to be performed to comply with state and federal laws (Ley Número 112 del 20 de julio de 1988, Ley para la Protección del Patrimonio Arqueológico Terrestre de Puerto Rico;

―Archaeological Resources Protection Act – 16 U.S.C. 470" y ―Protection of Historic and Cultural Properties - 36 CFR Part 800")). For the project ER-HWY-259 an archaeological evaluation was done to determine the presence or absence of cultural resources, historical sites, architectural and engineering structures that exist or are find on or under the surface of the earth. In this way we will comply with the requirements established by the Regulatory Agencies, the ―Instituto de Cultura Puertorriqueña (ICP) and the State Office of Historic Preservation (SHPO). A brief summary of the findings is revealed below. For a copy of the full document please refer to the Technical Appendix binder.

Table No. 7.1 Environmental Findings Summary

Task Findings Environmental Impact

Recommendation (Mitigation)

Cultural Resources Assessment Phase I

Negative Presence of Cultural Resources

No Impact None

Survey to Determine the Presence of Asbestos

Negative Presence of Asbestos

No Impact

None

Survey to Determine the Presence of Lead

Negative Presence of Lead No Impact

Habitat Categorization Dominant Flora Species:

Mangifera indica, Trichostigma octandrum, Cissus verticillata, Mikania amicrantha. No species of concern were observed.

Is the Site within or Adjacent to Protected Areas? The site is not located within or adjacent to protected areas.

Is the site within a Designated Critical Habitat?

The site is not located within a designated critical habitat.

Low Impact

The Proponent must prepare a mitigation planting plan

Tree Inventory and Mitigation planting plan

Potential Trees to be Removed: (l) Spondias mombin, (l) Cocos mucifera,

(2) Meliccocus bijugatus, (2) Mangifera indica. Removal of trees will depend on final design.

Low Impact The Proponent must prepare a mitigation planting plan

Task Findings Environmental Impact

Recommendation (Mitigation)

Biological Assessment Dominant Fauna Species:

Icterus dominiscensis portoricensis, Coereba flaveola, Ctenonotus cistellus. No species of concern were observed.

Potential Presence of Sensitive Resources:

Potential habitat for Chilabothrus inornatus.

Is the Site within the Range of Federally Protected Species Habitats? The site is within the range of the Chilabothrus inornatus.

Low Impact

Moderate Impact

The proponent must implement the protocol for the Boa of Puerto Rico, approved by the Department of Natural and Environmental Resources, September 2009

(USACE) Jurisdictional Determination (JD) Assessment

No wetlands, streams or rivers exist within the site.

No Impact None

8.0 GEOTECHNICAL INVESTIGATION

This report provides a summary of the activities performed during the course of the investigation, a description of subsurface conditions encountered at the site, and geotechnical recommendations for the design and construction of landslide stabilization alternatives for the project.

The project site contains one (1) landslide area on the outside edge of the roadway where part of the roadway was blocked with soil and rock debris which were removed with earthmoving equipment and trucks; some of this debris appears to have been pushed or dumped over the outside edge of the roadway.

The landslide area visually extends approximately 50 feet in length along the roadway and at least 40 feet in height. The geotechnical investigation performed consisted of drilling one (1) boring (BG-1) to a depth of 3 feet for a total of 3 lineal feet of drilling exploration (boring encountered refusal at that depth). The location of the boring at the site was established in the field by GeoCim by visual observation from existing local references; the presence of underground and areal utilities in the area and vehicle traffic requirements on the roadway were also taken into consideration in the selection of the location of the boring.

The approximate boring location is shown on Figure 2 – Boring Location Plan;

boring BG-1 was located adjacent to the landslide and at one end of the concrete barriers on the outer edge of the roadway.

8.1 GEOLOGY AND SUBSOIL CONDITIONS

Figure 3 of the Geotechnical Report, reproduces the portion of the Ciales Quadrangle geologic map prepared by the U.S. Geological Survey, (USGS) where in the PR-155, Km. 38.35 Landslide is located; the geological units present in the area are distinguished by different colors and letter symbols. The site sits within the outcrop of map unit Kop (purple-colored)which covers most of the map area shown. Unit Kop is identified as the Perchas Lava member of the Rio Orocovis Formation of upper Cretaceous age (over 65 million years old).

According to the USGS, the Perchas Lava consists of ―massive amygdaloidal pillow lavas and thin lenticular layers of tuff, epiclastic1 volcanic sandstone, and epiclastic volcanic breccia.‖ After deposition, these rocks experienced folding, faulting, and low grade metamorphism and the strata in the general site area are shown to presently exhibit northerly dips in the range of 15 to 65°, with those at the Km 38.35 landslide site shown to be dipping 15° almost due north. The geologic map also shows 3 high-angle geologic faults near the failure site with a number of other faults identified to the northwest, north, and northeast (Figure 3).

The three near faults include: 1-a north-northeast trending fault that crosses the roadway some 50 meters east of the site, 2-an approximately-located (shown by a dashed line) fault that begins at the former and passes just north of the roadway at the landslide site trending west-northwest, and 3- an east-northeast trending fault that begins just north of the landslide site.

We looked at the rock exposed at the landslide scar and the adjacent roadway cuts to the east and west (much of these surfaces are obscured by vegetation).

The rock consists of massive lavas that typically exhibit a porphyritic texture with a fine-grained matrix. It is typically highly to moderately weathered (Table 1 explains the terminology used to describe the rock) and friable to moderately strong, locally strong. Although no stratification was recognized, the rock is cut by closely- to little-spaced fractures that typically exhibit flat to undulated, relatively smooth surfaces. Fracture orientations vary widely with no prominent fracture sets evident; the majority exhibit high angle dips, but we observed several discontinuous fractures dipping north (out of the slope) at about 20° to 40° in the rock exposed within the landslide scar and the road cut to the west, where a smaller rockslide is presently active. This visual reconnaissance of the cut slope surface along the landslide scar from the roadway level also indicate that a mixture of soil and fractured rock is exposed at the surface with a higher amount of weathered rock in the lower 15 to 20 feet of the slope; this is consistent with a residual soil/weathered rock profile where generally the degree of weathering decreases with depth as the fresh rock is approached.

The subsurface conditions encountered at the site are in general agreement with those described in the geologic map. The subsoil profile seen in boring BG-1 consist of the Weathered Volcanic Rock Formation which is described as sampled as a fine grained Weathered Volcanic Rock in a very dense condition as indicated by N-values of over 100 bpf indicating virtual refusal to the penetration of the sampler and finally obtaining refusal to the penetration of the augers at 3 feet depth. Groundwater was not observed in the boring.

8.2 ANALYSIS, CONCLUSIONS AND RECOMMENDATIONS

The main objective of these recommendations is to provide stability to the reconstructed roadway in the landslide area.

Based on the results of the boring drilled and the site reconnaissance performed we understand that the landslide on the inside edge of the roadway in this area was a relatively shallow slide triggered during a heavy rainfall event such as Hurricane Maria when the surface soils and rock became saturated; additionally, erosion of the near surface soils and fractured rock may have also occurred due to uncontrolled surface water runoff over the top edge of the cut slope. A visual reconnaissance at the top (from a local access road of limited width providing access to several residential structures) and bottom (from PR-155) of the cut slope suggest that the cut slope is presently in a relatively stable condition as surface cracks at the top and bulging at the base of the cut were not observed.

However, the slope of the existing landslide scar remains at fairly steep angles between about 1(H):1(V) and 1(H):2(V) which poses some probability of further instability in the future. Although not included in the scope of this study, the existing cut slopes adjacent and on both sides to the landslide scar have steeper inclinations with currently active small shallow failures which may develop into larger areas of instability during future significant rainfall or earthquake ground shaking events.

The stabilization alternatives may include the following:

8.2.1 Gravity Retaining Wall

Gravity retaining wall such as a Gabion or Concrete wall – this will require an excavation of a minimum of about say 7 feet in order for the wall to bear on the underlying Weathered Volcanic Rock Formation. The location of the wall shall be established such that the top of the proposed wall extends to the edge of the reconstructed roadway; the final depth of the wall shall also provide for the outside bottom edge of the wall to be located a minimum of 3 to 5 feet from the outside edge of the Weathered Granodiorite strata on the existing slope which may be approximately established by the Designer using the topographic survey information. At the required excavation level an Allowable Soil Bearing Pressure (Qall) of 5,000 pounds per square foot (psf) may be utilized for wall design; PRHTA standard drawings for these walls may be utilized.

For a detailed design, the lateral pressures acting on the retaining wall shall be determined using a triangular earth pressure diagram acting on a vertical plane passing through the heel of the wall and extending from the bottom of the wall to the proposed ground surface. This triangular earth pressure diagram shall be calculated using an ―active‖ lateral earth pressure coefficient, Ka, and an angle of internal friction (Ø) of 32 degrees for the backfill material to be utilized; a unit weight (γ) of 130 pounds per cubic foot (pcf) may also be used for the backfill material behind the walls.

Any other surcharge loads acting on the ground surface at or near the walls must be added to the previously mentioned earth pressures to determine the final design lateral loads acting on the walls.

The above lateral earth pressure recommendations assume that the backfill material behind the wall will consist of an engineered compacted fill constructed as described under the Earthwork Recommendations section of this report. The backfill material within 10 feet from the wall shall be placed in 4 to 6 inch thick layers and compacted with light, hand operated compaction equipment to 90% of the maximum dry density as obtained in the Modified Proctor Test (ASTM D 1557). The backfill material beyond 10 feet from the wall shall be placed in 8 to 12 inches thick layers and each layer compacted to 95% of the maximum dry density as obtained in the Modified Proctor Test (ASTM D 1557) using conventional compaction equipment.

The retaining wall will include a drainage system that will provide a fast and efficient way to collect and dispose of any water that may infiltrate behind the wall in order to prevent the development of unbalanced water forces behind the wall; a typical drainage system would include a free draining crushed stone layer behind the retaining wall separated from the backfill material by a geotextile filter fabric (such as Mirafi 140N or equivalent), and a perforated drainage pipe placed at the bottom of the wall and connected to a proper outlet. Alternatively, other types of drainage composites specifically manufactured for drainage behind retaining walls may be used.

Prior to beginning construction of the retaining wall, the foundation bearing surface for the wall shall be cleaned and any soil disturbed during the excavation operations (or any time thereafter) shall be compacted or removed to provide an undisturbed soil bearing surface. We recommend that a Geotechnical Engineer and/or Engineering Geologist be present at the site when the landslide area is excavated in order to observe and confirm that the proposed excavation depths extend below the landslide sliding surface and that a firm bearing surface is reached; therefore, the final bearing surface for the retaining wall shall be determined in the field based on observations of the materials exposed by the excavation.

8.2.2 Reinforced Concrete Retaining Wall

Reinforced concrete retaining wall – in this alternative a reinforced concrete retaining wall may be designed following the same recommendations provided above for the Gravity Retaining Wall, including bearing on the Weathered Volcanic Rock Formation and the inclusion of adequate drainage measures behind the wall.

8.2.3. Mechanically Stabilized Earth Wall

Mechanically Stabilized Earth Wall – in this alternative this retaining wall may be designed following the same recommendations provided above for the Gravity Retaining Wall, including bearing on the Weathered Volcanic Rock Formation and the inclusion of adequate drainage measures behind the wall.

8.4 Earthwork Recommendations

The following general earthwork recommendations are provided for construction of any fill or backfill that may be required within the project in the landslide areas.

8.4.1. Prior to commencing construction the site shall be cleared and grubbed of vegetation cover and topsoil that may exist at the ground surface and any existing asphalt/concrete pavement from the existing roadway shall be demolished and removed from the site. After the clearing, grubbing, and demolition operations of the existing facilities are completed, and after any cut excavations are performed, the exposed surfaces shall then be proof-rolled with several passes of a heavy vibratory roller to detect any soft soil spot that may have to be removed and to densify any surface soil that may have been disturbed during the clearing and grubbing, and/or cut excavation operations.

8.4.2. Excavations into the existing very dense to hard Weathered Rock Formation near the ground surface and for evening out of the landslide scar surface will require the use of rock excavating equipment, including heavy duty impact hammers.

8.4.3. Materials from required cuts at the site shall not be used as Fill at the site. Fill and/or backfill material to be used at the site shall consist of a non-expansive A-2-4 soil or better in accordance with the AASHTO (American Association of State Highway and Transportation Officials) Soil Classification system. All fill within the site shall be placed as engineered compacted fill in 8 to 10 inch thick layers and each layer compacted to a minimum of 95% of the Maximum Dry Density as obtained in the Modified Proctor Test (ASTM D-1557); in excavations of limited extent the thickness of the fill layers placed shall be reduced to about 4 to 6 inches in order to attain the above compaction level. Fill required on sloped surfaces shall be placed in horizontal layers starting from the lower elevations and each horizontal layer shall be keyed into the in-situ soils so as to prevent the development of a preferred surface of sliding along the contact of the natural soils and the engineered compacted fill.

8.4.4 Temporary cut excavations deeper 4 feet within the very hard Weathered Rock Formation encountered within the lower portion of the existing cut slope shall be performed with slopes not steeper than 1(H):2(V); alternatively, the cut shall be properly braced and supported.

Since bracing and support of cut excavations is a temporary construction feature, the Contractor shall design and select the most suitable support system for the excavation equipment and technique that he will use in the project.

8.4.5 We recommend that final fill slopes (if any) be constructed at inclinations not to exceed 2(H):1(V). All fill slopes shall be properly and promptly vegetated in order to prevent excessive erosion of the soils that may cause instability of the slopes.

8.4.6 The project should be provided with adequate surface drainage measures to collect and conduct runoff to the project storm water system.

Under no circumstance should water be allowed to accumulate anywhere within the project or to spill over the recommended retaining walls and/or slope embankments.

9.0 RETAINING WALL ALTERNATIVES ANALYSIS AND

RECOMENDATIONS

Three alternatives are under consideration, and are assessed in detail in this Technical Report, the key aspects that were considered during the RWAA were:

Geotechnical constraints Earthwork, unclassified excavation for structures Environmental issues Traffic constrains Utilities Conflicts Right-of-way acquisition areas and social impacts

Physical environmental impacts Conceptual Cost Estimate Timeliness Network flexibility; and Route performance and safety Drainage

Table No. 9.1 Retaining Wall Alternatives Analysis

No. RW Type Description Advantages Disadvantages 1 Gravity retaining wall (Gabion or Concrete Wall)

Gravity retaining wall such as a Gabion or Concrete wall – this will require an excavation of a minimum of about say 7 feet in order for the wall to bear on the underlying Weathered Volcanic Rock Formation. The location of the wall shall be established such that the top of the proposed wall extends to the edge of the reconstructed roadway; the final depth of the wall shall also provide for the outside bottom edge of the wall to be located a minimum of 3 to 5 feet from the outside edge of the Weathered Granodiorite strata on the existing slope which may be approximately established by the Designer using the topographic survey information. At the required excavation level an Allowable Soil Bearing Pressure (Qall) of 5,000 pounds per square foot (psf) may be utilized for wall design;

Moderate disturbance of the roadway lanes during construction process.

Gabion wall has better drainage performance than other alternatives.

Moderate Cost.

Gabion wall has the capability to integrate vegetation at the façade to integrate them to the surrounding area.

Larger amount of earthwork movement at the cut slope to accommodate the footprint of the retaining wall outside of the roadway path.

2 Reinforced concrete retaining wall

In this alternative a reinforced concrete retaining wall may be designed following the same recommendations provided above for the Gravity Retaining Wall, including bearing on the Weathered Volcanic Rock Formation and the inclusion of adequate drainage measures behind the wall.

Moderate amount of earthwork movement at the cut slope.

Constructed using common materials.

Can be ground-anchored to provide capacity.

Higher Cost.

Higher negative impact on the existing roadway and traffic patch

Require a large space. Unsuited to displacement-based design approach, as need anchors for significant height.

3 Mechanically Stabilized Earth Wall

In this alternative this retaining wall may be designed following the same recommendations provided above for the Gravity Retaining Wall, including bearing on the Weathered Volcanic Rock Formation and the inclusion of adequate drainage measures behind the wall.

Moderate construction time and impact on existing on cut slope.

Lowest negative impact on roadway lanes.

Moderate cost.

Moderate Construction time.

Moderate negative impact on roadway lane.

Moderate negative impact on the utilities under roadway area.

Table No. 9.2 Retaining Wall Alternatives Cost Summary

Retaining Walls Alternatives Description

RT Wall Height Range

Reinf.

Conc. RW

MSE Wall Reinf.

Shotcrete

Gravity Gabions

Wall

Gravity Conc. Wall

Reinf.

Slope

0 - 3 Mts. $ 105.00 $ 96.00 $ 70.00 $ 61.00 $ 180.00 $ 48.00

3 - 5 Mts. $ 121.00 $ 110.00 $ 77.00 $ 70.00 $ 208.00 $ 57.00

5 - 7 Mts. $ 138.00 $ 127.00 $ 88.00 $ 84.00 $ 239.00 $ 68.00

7 10 Mts. $ 159.00 $ 146.00 $ 101.00 $ 98.00 $ 275.00 $ 81.00

Table No. 9.3 Retaining Wall Alternatives Rating Matrix (RWARM)

Criteria

Description

G eo te ch ni ca l

C on st ra in s

E ar th w or k

M ov em en t

E nv iro nm en ta l

Is su es

U til iti es

C on fli ct s

R ig ht -o f-w ay

P hy si ca l en vi ro nm en ta l

Im pa ct s

C on ce pt ua l

C os t E st im at e

T im el in es s

R ou te

P er fo rm an ce

D ra in ag e

TOTAL

Weight 15 10 6 8 14 6 10 10 15 6 100

A lt er n at iv e

Reinf. Conc 10 7 6 6 8 5 7 5 10 5 69

MSE Wall 15 10 6 7 12 5 7 8 12 5 87

Gravity Wall 10 8 6 6 8 5 10 10 10 6 79

9.1 Retaining Wall Recommendations

Based on the retaining wall types described in this report, with advantages and disadvantages shown in the table 9.1, the Retaining Walls Alternatives Cost Summary shown in the table 9.2 and the Retaining Wall Alternatives Rating Matrix (table 9.3) values we can concluded that in term of the environmental issues and physical environmental impacts all alternatives have a similar effect, since the landslide has affected the area and it continues to erode due to local factors, mainly rain. In term of the underground and aerial utilities all alternatives have the same impact. With the greatest negative effect on the construction timeline and on existing traffic, the least recommended alternative is Reinforced Concrete Retaining Wall. There is no expectation or negative social impacts for any alternative for this site.

The alternative Reinforced Concrete Retaining Wall has the higher cost and even moderate is the impact in the traffic, route performance and safety, and the construction timeline; therefore it is the second recommended alternative.

Because the alternative Gravity Retaining Wall presents the higher negative impact on the roadway area and traffic, higher negative impact on the utilities under roadway area, is the least recommended alternative.

The alternative with the higher score, 87 in the RWARM, is MSE Wall, is presented as the preferred alternative for this site because of the moderate cost,…