Report_Geotechnical_ER-HWY-63.pdf

GEOTECHNICAL SUBSOIL

EXPLORATION AND

REPORT ON LANDSLIDE AT

PR-119, KM. 32.1

SAN SEBASTIÁN, PUERTO RICO

Suelos, PSC Calle Chile 258, San Juan, P.R. 00917-2103 Tel. (787) 753-0147. Emails: suelosinc@gmail.com / jackson.suelos@gmail.com mailto:suelosinc@gmail.com mailto:jackson.suelos@gmail.com

Suelos, PSC

Soil & Construction Materials Laboratory and Environmental Drilling Services

GEOTECHNICAL SUBSOIL EXPLORATION AND

REPORT ON LANDSLIDE AT PR-119, KM. 32.1

SAN SEBASTIÁN, PUERTO RICO

CMA, ARCHITECTS & ENGINEERS

*Prepared for*

Boring Logs Performed & Supervised By

*SUELOS, PSC.

Submitted on November 6, 2018 Job No. 4813.rep

258 Chile St., San Juan, PR 00917-2103. Phone (787) 753-0147 Emails: suelosinc@gmail.com / jackson.suelos@gmail.com mailto:jackson.suelos@gmail.co

GEOTECHNICAL SUBSOIL EXPLORATION AND

REPORT ON LANDSLIDE AT PR-119, KM. 32.1

SAN SEBASTIÁN, PUERTO RICO

November 6, 2018

TABLE OF CONTENTS

1.0 INTRODUCTION

2.0 SITE LOCATION AND MORPHOLOGY OF AFFECTED AREA

3.0 WORK PERFORMED

4.0 GENERAL GEOLOGY

5.0 SUBSOIL CONDITIONS

5.1 First Stratum

5.2 Second Layer

6.0 GROUNDWATER LEVELS

7.0 INCLINOMETER

8.0 DISCUSSION

9.0 SLOPE STABILITY ANALYSES AT REPRESENTATIVE CROSS SECTION

(STATION 1+35)

9.1 Strength Parameters Based on Empirical Correlations

10.0 ANALYSES FOR LONG TERM STABILITY AND RECOMMENDATIONS . . . 10

10.1 Alternative #1: Slope Reconstruction

10.2 Alternative #2: Gabion Wall Construction

10.3 Alternative #3: Soldier Pile + Lagging

11.0 FIELD MONITORING

12.0 ADDITIONAL CONSIDERATIONS

13.0 LIMITATION OF REPORT

14.0 GENERAL COMMENTS

BORING LOGS

DRILLING APPENDIXES

Suelos, PSC.

258 Chile St., San Juan, P.R. 00917-2103 Phone (787) 753-0147. Emails: suelosinc@gmail.com / jackson.suelos@gmail.com

Suelos, PSC.

Soil & Construction Materials Laboratory and Environmental Drilling Services

Figure 1. Site location

GEOTECHNICAL SUBSOIL EXPLORATION AND

REPORT ON LANDSLIDE AT PR-119, KM. 32.1

SAN SEBASTIÁN, PUERTO RICO

1.0 INTRODUCTION

This report presents the results of a Geotechnical Exploration performed at a site where slope instability problems have been observed in State Road PR-119, Km. 32.1, San Sebastián, Puerto

Rico.

The work was performed at the request of Eng. José Carro, on behalf of CMA, Architects

& Engineers, following the scope of work presented in our technical proposal.

The purpose of the exploration was to establish the physical properties of the subsurface soils in order to present possible alternatives for remedial works.

2.0 SITE LOCATION AND MORPHOLOGY OF AFFECTED AREA

The slope failure is located at Km. 32.1 of PR-119, just 1.3 miles to the north of the intersection with PR-111, in San Sebastián, Puerto Rico. Figure 1 shows the project location depicted on a copy of the topographic map.

SAN SEBASTIÁN, PUERTO RICO

November 6, 2018

Figure 2. Aerial view of affected area

Figure 2 shows an aerial view of the affected road. The local topography within the affected area grades downward from north to south with an overall relief of some 5 meters measured from

PR-119 average elevation. According to the plans provided and field data gathered, the landslide affected the southbound lane and south shoulder of PR-119. Refer to Figure 3 for present conditions of the road at Km. 32.1.

At the study site the failure corresponds to a landslide which involves an approximate length of 20 meters (in plan view). The approximate landslide extension from the head scarp to its toe is

18 meters. Its most obvious manifestation is a half moon depression at the southbound lane of

PR#119, which forms the uppermost boundary of the landslide (the head scarp). The general movement of the landslide heads towards the south.

Suelos, PSC.

258 Chile St., San Juan, P.R. 00917-2103 Phone (787) 753-0147. Emails: suelosinc@gmail.com / jackson.suelos@gmail.com

SAN SEBASTIÁN, PUERTO RICO

November 6, 2018

Figure 3. Present conditions at km. 32.1

3.0 WORK PERFORMED

A total of two (2) boreholes were drilled to a depth of 35 feet. The boring locations are shown on the site plan included as Figure 4. The boring logs are included as an Appendix to this report.

Suelos, PSC.

258 Chile St., San Juan, P.R. 00917-2103 Phone (787) 753-0147. Emails: suelosinc@gmail.com / jackson.suelos@gmail.com

SAN SEBASTIÁN, PUERTO RICO

November 6, 2018

Figure 4. Boring locations

Various Atterberg Limit tests were carried out on selected samples to perform parametric correlations with shear resistance. Also, one inclinometer was installed at the location of boring #1 for the monitoring of ground movements.

A review of available geologic and topographic data was also performed. Site visits and geologic reconnaissances were conducted during the field work. Finally, all the information was gathered and used to prepare a subsurface model for the stability evaluation and for developing mitigation recommendations.

Suelos, PSC.

258 Chile St., San Juan, P.R. 00917-2103 Phone (787) 753-0147. Emails: suelosinc@gmail.com / jackson.suelos@gmail.com

SAN SEBASTIÁN, PUERTO RICO

November 6, 2018

Figure 5. Geologic setting

4.0 GENERAL GEOLOGY

Figure 5 shows portion of the San Sebastián Geologic Quadrangle with the site approximately circled. According to this source of information, the site is underlaid by the Lares

Limestone and Landslide Deposits. These geologic units consist of the following:

1) Lares Limestone (Tl): Dominantly light brown and very pale orange to white, nearly pure limestone.

2) Landslide Deposits (Ql): Unconsolidated deposits of clayey earth and rock with blocks of limestone.

Suelos, PSC.

258 Chile St., San Juan, P.R. 00917-2103 Phone (787) 753-0147. Emails: suelosinc@gmail.com / jackson.suelos@gmail.com

SAN SEBASTIÁN, PUERTO RICO

November 6, 2018

5.0 SUBSOIL CONDITIONS

The test holes drilled for the exploration revealed fairly consistent subsurface conditions from borehole to borehole, but the typically light brown and very pale orange to white, nearly pure limestone of the area was not encountered. Rather, the test holes disclosed an upper layer of fill and colluvium associated with the construction of PR-119, and old landslides by the San Sebastián

Formation. The Lares Limestone was not found within the explored depth.

The conditions revealed by the borings can be generally summarized as follows:

5.1 First Stratum

The first horizon consists of 13 ft of fill and/or colluvium material comprised of clay with some to little sand. This material was found at the particular boring locations and it is probably associated to road PR-119 construction and/or very old landslide activity.

During the sampling operations the Standard Penetration Tests (SPT) obtained N-values from

7 to 30 blows per foot (bpf), most of then between 7 and 12 bpf. Natural Moisture Contents range between 25 and 37 percent.

It is worth noting that the soil debris left by the sliding mass appears to be fill material rather than landslide deposits. Based on this, it is reasonable to think that the sliding mass was chiefly comprised of fill material.

5.2 Second Layer

Below the fill layer, the San Sebastián Formation was encountered. This is made of clay, silt and sand in variable proportions. Grayish-brown, yellowish-brown and olive yellow are the prevailing color tones. Consistency, based on SPT values and Unconfined Compressive Strength, varies from stiff to very stiff. The Natural Moisture Content ranges from 20 to 32 percent. Figure

6 shows a schematic representation of the approximate soil profile.

Suelos, PSC.

258 Chile St., San Juan, P.R. 00917-2103 Phone (787) 753-0147. Emails: suelosinc@gmail.com / jackson.suelos@gmail.com

SAN SEBASTIÁN, PUERTO RICO

November 6, 2018

Figure 6

Suelos, PSC.

258 Chile St., San Juan, P.R. 00917-2103 Phone (787) 753-0147. Emails: suelosinc@gmail.com / jackson.suelos@gmail.com

SAN SEBASTIÁN, PUERTO RICO

November 6, 2018

6.0 GROUNDWATER LEVELS

As part of the investigation, one (1) observation well (OW) was installed to observe the existence and variation in the groundwater table.

The following table shows the groundwater table level as recorded from the observation well at various dates after drilling.

TABLE 1; GWT Recorded in MW

Date of Reading Observation Well or Boring GWT (ft)

11/02/18 B-2 Not Observed

10/31/18 B-2 Not Observed

10/29/18 B-2 Not Observed

7.0 INCLINOMETER

One (1) inclinometer was installed at the area of interest to investigate possible slope movements. The inclinometer is made of a plastic casing with internal vertical grooves used to guide a probe which record changes in the slope of the casing. By comparing the slopes of present and previous readings, movements can be detected.

Reference (zero) reading were taken on 10/26/2018. Subsequent readings were taken on

10/31/2018 and 11/6/2018. A summary of the inclinometer data is presented as an Appendix to this report.

During the monitoring period (10/26/18 to 11/31/2018) the inclinometer installed by Suelos, PSC. has not recorded evident subsurface motion. The small, arbitrary movements plotted by the inclinometer can be attributed to either systematic errors of the instrument or variances in field reading techniques. Based on this finding, a deep seated rotational landslides has not developed at the site. The slope instability observed at Km. 32.1 appears to be a localized, shallow landslide within the fill layer or the very old colluvium.

Suelos, PSC.

258 Chile St., San Juan, P.R. 00917-2103 Phone (787) 753-0147. Emails: suelosinc@gmail.com / jackson.suelos@gmail.com

SAN SEBASTIÁN, PUERTO RICO

November 6, 2018

8.0 DISCUSSION

In our opinion, the localized landslide has evolved from the combination of a steep slope geometry, the presence of weak fill and possibly, significant run-off water. Considering that the hill slope follows a steep angle and shows loose to medium density, it is conceived that severe weather conditions and extraordinary precipitation would tend to decrease the safety factor of the current slope. This has triggered instability problems in the hillside jeopardizing the integrity of PR-119 around km 32.1.

The following sections discuss possible remedial measures to improve the stability of the hillside at km 32.1. In plan view, the selected alternative shall span from Sta. 1+20 to 1+52. Refer to Figure 4 for stationing.

9.0 SLOPE STABILITY ANALYSES AT REPRESENTATIVE CROSS SECTION

(STATION 1+35)

9.1 Strength Parameters Based on Empirical Correlations

The fill material and older alluvial deposits are essentially plastic soils. Correlations for estimating the effective stress friction angle for cohesive soils have been presented by numerous authors including Terzaghi, Peck, Meyerhof and Schmertm and, and Stark and Eid, 1994,1997.

Once the shear strength characteristics were identified the next step was to create a simplified soil model to run stability analyses. The stability analyses were performed by using Bishop, Janbu and Morgenstern-Price slope stability methods of slices for circular, non-circular and combined sliding surfaces(Geolslope 5 Software was used for th analyses.).

In slope stability evaluations a safety factor can be defined as the ratio of the "forces trying to prevent failure” (F.P.) divided by the "forces trying to induce failure" (F.I.).

The following conditions may occur:

% F.P./F.I. > 1.0 The slope is considered stable (usually 1.5 minimum for long term stability).

% F.P./F.I. = 1 Failure is forthcoming.

% F.P./F.I. < 1 Failure has occurred.

Suelos, PSC.

258 Chile St., San Juan, P.R. 00917-2103 Phone (787) 753-0147. Emails: suelosinc@gmail.com / jackson.suelos@gmail.com

SAN SEBASTIÁN, PUERTO RICO

November 6, 2018

Therefore, a safety factor of 1 (or close to 1) indicates incipient failure. No formal criteria for establishing threshold safety factors has been formally published by a regulating agency for the stability of slopes. Many technical papers have been published on the subject suggesting particular minimum values of factors of safety depending, among other things, on the methods of subsurface exploratory sampling (disturbed versus undisturbed sampling), laboratory testing for soil strength determination, and soil strength conditions (short term versus long term conditions). A common denominator to most of these papers, after the particular slope has been thoroughly modeled, is that each case analyzed is unique and specific to that site. Technical knowledge on site specific soil strength determination, added to previous experience within the site, diminishes the degree of uncertainties related to the modeling of the stability of the slope and leaves the final decisions to be based on engineering judgement.

The criteria used for the slope stability analyzes in this report is as follows:

Condition Acceptable Safety Factor

Static 1.5

Pseudo Static 1.1

10.0 ANALYSES FOR LONG TERM STABILITY AND RECOMMENDATIONS

Detailed stability analyses were performed in order to investigate the future factor of safety of the hillside for three (3) possible remedial measures.

The position of the groundwater table was not considered in our analyses as a stabilized groundwater table was not found during field work. In addition, the existing drainage system at the study area controls the run-off water coming from north side slope and along PR-119. We are considering that the storm-water drainage system will be improved as required and/or maintained in working conditions. The soil parameters used were:

Suelos, PSC.

258 Chile St., San Juan, P.R. 00917-2103 Phone (787) 753-0147. Emails: suelosinc@gmail.com / jackson.suelos@gmail.com

New Fill: Unit weight 130 pcf , Angle of internal Friction; 32 degrees, cohesion: 200 psf In-situ clayey soils: Unit Weight: 120 pcf, Angle of internal friction:17 degrees, cohesion: 100 psf San Sebastian Formation: Unit weight: 130 pcf, Phi residual:17 degrees, cohesion 1000 psf Gabion wall:Unit weight: 140 pcf, angle of internal friction: 40 degrees,, cohesion :0

SAN SEBASTIÁN, PUERTO RICO

November 6, 2018

Figure 7

Due to the relatively small topographic relieve between the PR-119 elevation and the toe of the landslide (about 17 feet), the following possible alternatives can be considered:

1. Slope reconstruction

2. Gabion wall construction near the edge of PR-119

3. Cantilever soldier pile/lagging wall near the edge of PR-119

The implementation of these remedial measures in the slope stability analyses lead to a safety factor greater than 1.5 for static conditions and1.2 under seismic acceleration of 0.15g. A schematic representation of the long term stability alternative for slope reconstruction is presented in Figure

7.

Suelos, PSC.

258 Chile St., San Juan, P.R. 00917-2103 Phone (787) 753-0147. Emails: suelosinc@gmail.com / jackson.suelos@gmail.com in-situ soils Fill

San Sebnastian Formation

SAN SEBASTIÁN, PUERTO RICO

November 6, 2018

10.1 Alternative #1: Slope Reconstruction

This alternative consists of excavating the unstable soils down to 4 meters deep until reaching the competent San Sebastián Formation, and replacing the excavated soils with select A-1-a material compacted to 95% Modified Proctor.

Figure 8 is a schematic representation of the slope reconstruction alternative where the weak material is removed and the exposed surface benched and conditioned. When performing the slope reconstruction, filling shall begin in the lowest section of the area, atop the stiff clays comprising

San Sebastián Formation. The select fill (A-1-a) shall be placed over properly conditioned and proof rolled subgrade, and compacted in 12-inch lifts. During compaction, a minimum density corresponding to 95% of the material maximum density (Modified Proctor Tests) shall be attained.

Final slope geometry shall be 1.5H:1V or flater.

Prior to the construction of the new fill embankment, the sloped surface to be filled should be stepped in order to key-in the new A-1-a fill. Under no circumstances the fill should be placed over a sloping ground surface without first benching the ground surface.

Benching requirements shall be decided by the observing resident Soil Engineer, depending on actual field conditions.

Suelos, PSC.

258 Chile St., San Juan, P.R. 00917-2103 Phone (787) 753-0147. Emails: suelosinc@gmail.com / jackson.suelos@gmail.com

SAN SEBASTIÁN, PUERTO RICO

November 6, 2018

Figure 8. Alternative #1: Slope Reconstruction to 1.5H:1V.

Suelos, PSC.

258 Chile St., San Juan, P.R. 00917-2103 Phone (787) 753-0147. Emails: suelosinc@gmail.com / jackson.suelos@gmail.com

SAN SEBASTIÁN, PUERTO RICO

November 6, 2018

Figure 9

10.2 Alternative #2: Gabion Wall Construction

Under this alternative, a gravity gabion wall about 16 feet high should be constructed over the stiff clay layer located about 4 meters deep below PR-119 elevation. For design, an allowable soil bearing capacity of 3,500 psf can be safely used, provided a minimum depth of foundation of

5 ft is allowed. Behind the wall, new compacted fill will be necessary for the reconstruction of PR-

119. This backfill can consider A-2-4 or better fill material. Refer to Figure 9.

Suelos, PSC.

258 Chile St., San Juan, P.R. 00917-2103 Phone (787) 753-0147. Emails: suelosinc@gmail.com / jackson.suelos@gmail.com

SAN SEBASTIÁN, PUERTO RICO

November 6, 2018

The gabion wall shall be provided with a minimum depth of foundation (Df) of 1.5 meters

(5 ft). Foundation baskets shall be laid on top of the stiff clay and/or properly conditioned subgrade.

Additional Df may be required by the wall designer if deemed necessary to increase sliding resistance. A 8-inch HDPE flexible perforated pipe drain shall be installed behind the concrete wall to properly discharge any infiltrating water.

10.3 Alternative #3: Soldier Pile + Lagging

For the case of the soldier pile wall, W12x53 piles shall be installed at a spacing of 2 mt c-c, and to a minimum depth of 9 meters measured from PR-119 elevation (see Figure 10). Precast or cast-in-placed concrete panels may be considered between each pile in order to support the new fill material necessary for the re-construction of PR-119. The concrete panels shall be embedded a minimum of 1 meter below grade (below current sloping ground), to protect the new fill material from eroding beneath the base concrete panel. Concrete panels shall be designed by a structural engineer to resist shear forces and bending moments of the new fill wedge, which will be about 2 meters high. Traffic loads shall also be considered.

Designer must take into consideration hydrostatic pressures, which shall be added to the force and stress envelopes. Likewise, if the designer wants to consider earthquake loading, the additional forces resulting from ground acceleration shall be added to the pressures obtained for the static condition. The earth pressure coefficient for dynamic increase in lateral force can be approximated as 75 percent of kh, kh being the expected horizontal acceleration in g’s. That is, for a given wall subjected to an active “static” pressure (Pa) equal to 0.5@ã@H2@Ka, the combined effect of static and dynamic force (Pae) would be (0.5@ã@H2@Ka) + (0.5@ã@H2@75% kh). An internal friction angle of 26 degrees can be used for the determination of Ka.

Suelos, PSC.

258 Chile St., San Juan, P.R. 00917-2103 Phone (787) 753-0147. Emails: suelosinc@gmail.com / jackson.suelos@gmail.com

SAN SEBASTIÁN, PUERTO RICO

November 6, 2018

Figure 10

11.0 FIELD MONITORING

As it is always the case for this type of geotechnical problems, field monitoring must be conducted during and after construction of the long term remedial measure to carefully evaluate its effectiveness and detect any problem that may occur during construction. The field monitoring will consist of periodical measurements from a control bench marks, and inclinometers installed. During construction the instrumentation must be read at least three (3) times per week.

The results of this monitoring program will provide any need to have to incorporate additional control measures. This monitoring program needs to be evaluated weekly during construction and monthly thereafter.

Suelos, PSC.

258 Chile St., San Juan, P.R. 00917-2103 Phone (787) 753-0147. Emails: suelosinc@gmail.com / jackson.suelos@gmail.com

SAN SEBASTIÁN, PUERTO RICO

November 6, 2018

12.0 ADDITIONAL CONSIDERATIONS

The long term remedial measures presented in this report require to strictly enforce closely-sequenced construction methods, where the excavation for benching and filling in any part of the hillside area occur in a close sequence such that the length of open excavations is left to a practical minimum at all times during the work day.

It is imperative that all reconstruction and stabilization works must be accompanied by a careful monitoring program, during and after construction, that will help in assessing the effectiveness of the recommended interim remedial measures. Although long term remedial measures given herein should be effective in minimizing future landslides at the hillside, variations in the site soil conditions, may require some changes in the stabilization program that can be promptly implemented with the help of the field instrumentation measurements in the hands of a well experienced geotechnical engineer. Therefore, it is recommended to adopt the field monitoring program as a component of the remedial measures suggested for this project.

The exact amount of this instrumentation will be determined by the Soil Engineer in charge of the geotechnical inspection during construction, as the site conditions dictate the requirement of the instrumentation. A typical monitoring station shall consist of control bench marks and inclinometers.

The control of surface runoff waters in this project is of paramount importance. An effective surface drainage system will have to be provided in this project, including (but not limited to) paved ditches, swales and interceptors, in order to properly collect and dispose surface and groundwater to properly designed outlets, both during construction and after the hillside has been repaired. Run-off shall not be permitted to run freely during nor after the remediate has been completed. Road run-off shall not be disposed on the ground. This run-off shall be diverted by meas of the required piping, ditches, culverts, and other hydraulic works into properly designed outlets out and way from the project.

Suelos, PSC.

258 Chile St., San Juan, P.R. 00917-2103 Phone (787) 753-0147. Emails: suelosinc@gmail.com / jackson.suelos@gmail.com

SAN SEBASTIÁN, PUERTO RICO

November 6, 2018

Weak fills or incompetent soils are present on the current sloping ground (landslide debris).

This debris must be fully removed before starting the new filling operation. The contractor shall follow all cleaning, stripping and benching recommendations presented by Suelos, Inc., full time soil technician and geotechnical engineer field supervisor. The actual depth and extension of removal shall be identified at the field during actual earthworks.

13.0 LIMITATION OF REPORT

This report has been prepared taking into consideration the design factors presently known to us. The project designers shall be alert of any item that might have been overlooked, that could require clarification or that may need additional recommendations to those discussed herein.

This report specifically covers analyses and evaluations on global or overall stability. The stability of the gravity wall alternative must also be checked against:

1. Internal Stability

2. Bearing Capacity

3. Sliding along the base

4. Overturning of the wall

The soil parameters used to model the stability analyses were based on our experience and existing empirical relationships. If the project owner wishes to refine the soil parameters presenter in this report, we strongly recommend the collection of various undisturbed soil samples to run special laboratory tests (triaxial and or direct shear tests).

Suelos, PSC.

258 Chile St., San Juan, P.R. 00917-2103 Phone (787) 753-0147. Emails: suelosinc@gmail.com / jackson.suelos@gmail.com

SAN SEBASTIÁN, PUERTO RICO

November 6, 2018

14.0 GENERAL COMMENTS

The inspection or supervision of excavations, foundations, earthworks and wall construction is, in general, is a very delicate matter. In some cases this service is not rendered by the Soils

Engineer who made the subsoil investigation and recommended the specific foundation alternatives for a given project. In a large number of projects these operations are successfully completed due to the prevalence of ideal and uniform conditions and to the fact that they are being performed by a competent and responsible contractor. But there are cases, where the lack of proper construction techniques and the lack of adequate supervision has given rise to the occurrence of foundation problems and failures.

Conscious of the above exposed problem, we wish to state that the validity of our recommendations about global stability are subordinated to the inspection of the foundation work operations by us. If the contract is awarded to another experienced Soils Engineer, he shall receive a copy of this report, evaluate the same and adopt it as his own, or request additional soil data to verify our foundation recommendations or modify them in accordance to his personal knowledge and judgement, thus assuming full responsibility for his recommendations and the report itself.

Respectfully submitted, IVAN JACKSON MADURO, P.E., M.S.C.E., CWI

Partner mgn

Reference No. 4813.rep

Suelos, PSC.

258 Chile St., San Juan, P.R. 00917-2103 Phone (787) 753-0147. Emails: suelosinc@gmail.com / jackson.suelos@gmail.com

BORING LOGS

Calle Chile 258, San Juan, P.R. 00917-2103 Tel. (787) 753-0147. Email: suelosinc@gmail.com

BORING LOGS

The description of subsurface profile and results of field and laboratory tests, as enclosed, pertain to conditions actually encountered at the borings location proper and at the depths indicated.

Profile tracings between borings, when give, represent a reasonable interpolation of subsoil characteristics and should not be taken to indicate true intermediate conditions.

NOTES:

N - Number of blows required to drive the sampling spoon a distance of 12" with a 140 lbs hammer falling 30".

NW - No water.

WH - Weight of hammer.

WR - Weight of Rods.

W - Natural moisture content in % of dry weight.

qu - Unconfined compressive strength in tons/sq ft.

* - Penetrometer value.

Suelos, PSC

33-29-21

12-8-5

4-4-7

6-9-10

21-12-16

9-14-16

8-15-21

17-26-41

33-57/3"--

50/2"-----

BLACK ASPHALT

Fill composed of clay and gravel olive gray

-same as above;

-same as above;

Dark brown sandy silt with fine to medium gravel-grayish-brown to olive yellow

-same as above; yellowish brown clayey sandy silt

Yellowish-brown stiff to hard silty clay

-same as above; some sand

-same as above;

Hard silty clay yellowish-brown

END OF TEST HOLE - 35.5 FT

57/3"

50/2"

3.5

4.5

4.0

SUELOS, INC. BORING NO.: B-1

Soil and Construction Materials Laboratory Job No. 4813

SUBSURFACE EXPLORATION LOG

PROJECT: LANDSLIDE AT PR-119, KM. 32.1, SAN SEBASTIAN, P.R.

Spoon : 1.375" I.D.

Driller : J. CALDERON Date Started : 11/05/18 WATER LEVEL: N < 100 = 35.5 Hammer: 140# Method : AUGER Date Completed: 11/05/18 Date : 11/05/18 N > 100 = Drop : 30" Drill Type: CME-45 Total Depth : 35.5 Depth: N/O CORE =

"N" values are the number of blows required to drive the sampling spoon a distance of twelve inches with a 140 lbs hammer falling 30 inches. Natural Moisture Content (2) is expressed in percentage of its dry weight. Unconfined Compressive Strength (Qu) values are expressed in tons per square foot. *Pocket penetrometer values are marked with an asterisk.

Depth ft

Samp No.

Recov

S.P.T.

values

RQD

Description of material

SPT-N

values

Qu

TSF

Moist Cont%

Sheet 1 of 1

55-40-23

20-17-13

5-4-3

4-4-4

3-5-7

5-5-8

7-11-13

9-15-18

16-29-44

50/5"-----

BLACK ASPHALT

Fill: clay some sand and little rock fragments (caliche), olive gray

-same as above;

Clay little sand, pebbles olive gray

-same as above; dark brown

Clay, sand traces some cemented silt, very dark grayish brown, olive yellow

Clayey silt, trace sand olive yellow

Silty clay sand traces, yellowish brown

-same as above; little sand

-same as above;

END OF TEST HOLE - 35.5 FT

50/5"

2.5

3.0

3.5

4.0

SUELOS, INC. BORING NO.: B-2

Soil and Construction Materials Laboratory Job No. 4813

SUBSURFACE EXPLORATION LOG

PROJECT: LANDSLIDE AT PR-119, KM. 32.1, SAN SEBASTIAN, P.R.

Spoon : 1.375" I.D.

Driller : J. CALDERON Date Started : 10/19/18 WATER LEVEL: N < 100 = 35.5 Hammer: 140# Method : AUGER Date Completed: 10/19/18 Date : 10/19/18 N > 100 = Drop : 30" Drill Type: CME-45 Total Depth : 35.5 Depth: N/O CORE =

"N" values are the number of blows required to drive the sampling spoon a distance of twelve inches with a 140 lbs hammer falling 30 inches. Natural Moisture Content (2) is expressed in percentage of its dry weight. Unconfined Compressive Strength (Qu) values are expressed in tons per square foot. *Pocket penetrometer values are marked with an asterisk.

Depth ft

Samp No.

Recov

S.P.T.

values

RQD

Description of material

SPT-N

values

Qu

TSF

Moist Cont%

Sheet 1 of 1

DRILLING APPENDIX

APPENDIX NO. 1

General

Comprised in this report is a description of the project as made know to SUELOS, PSC. and details of the project with pertinent recommendations for the design of foundations and other earth related structures. It should be considered that the design recommendations are relative to the project aspects discussed and subject to the limitations imposed by all practical considerations in the determination of subsoil conditions.

The field and laboratory data shown in boring logs represent subsoil conditions encountered at the borehole proper. The analysis and conclusions herein presented and discussed are based on such results and on a reasonable interpolation of subsoil characteristics. Whenever cross-sections with a schematic representation of the interpreted subsoil stratification between borings are included, the same should not be taken to represent true intermediate conditions but are rather given for general comparison purposes only.

Copy of this report should be made available to the Project Designers for their information and guidance, as well as to the Contractor and Resident Engineer, in order to secure maximum protection in the case of possible unexpected variations. Any such variations as well as any changes or modifications to the scope of project described after submittance of this report shall be notified by writing to these Consultants in order to evaluate same and decide upon the need to alter or modify the recommendations given.

Suelos, PSC

APPENDIX NO. 2

Field and Laboratory Work

Field exploration was made by SUELOS, PSC., a private laboratory to the services of these

Consultants. The field work consisted of a visual observation of the area and existing structures at the site, if any, and of performance of test borings as indicated.

Test borings were made in accordance to the "Standard Penetration Test and Split-Spoon

Sampling of Soils Method", as proposed by the Standards of the American Society for testing and

Materials Designation ASTM D-1586, Latest Revision.

The testing hole is bored either by manual and mechanical augers or by driving a 2.5 inch inside diameter casing into the ground which is washed clean internally each time a soil sample is to be secured below its reach. While sampling, the Standard Penetration Test is performed and the

"N" values recorded. This is the number of blows required to drive the split-spoon sampler 12 inches into the ground using a 140 lbs. hammer with a free fall of 30 inches.

The value gives an indication of the consistency of cohesive soils and the relative density of granular soils as shown in the following table:

COHESIVE SOILS

"N" Values Consistency Unconfined Comp. Strength

(TSF)

less than 2 very soft less than 0.25

2 - 4 soft 0.25 - 0.50

4 - 8 medium 0.50 - 1.00

8 - 15 stiff 1.00 - 2.00

15 - 30 very stiff 2.00 - 4.00 over 30 hard over 4.00

Suelos, PSC

Appendix No. 2

GRANULAR SOILS

"N" Values Relative Density

0 - 5 very loose

5 - 10 loose

10 - 30 medium

30 - 50 dense over 50 very dense

Depth of water surface shown on logs indicate the phreatic level found either prior to use of any casing and water or taken 24 hours after the test borings was completed and the casing, if any, is pulled out. The information given, unless otherwise indicated, is not a adequate for study of deep excavations and is only to be used as an approximate level in the study of a normal foundation of the project. Phreatic or underground water levels may vary with seasonal rainshower variations thus water may appear where none is shown and the reader of this report should be aware of this fact.

For excavations where ground water levels are of utmost importance special studies consisting of long range observations on installed wellpoint-type devices should be performed. Where deep excavations are contemplated, as in pumping stations, study of artesian or sub-artesian aquifers should be made by means of deep test borings and pumping tests.

Suelos, PSC

DIAMOND CORE DRILLING

Whenever drilling through rock is necessary the same is made following the "Diamond Core

Drilling for Site Investigation" method as proposed by the standards of the American Society for

Testing and Materials Designation ASTM D-2113-L.R. In general a double tube core barrel with diamond bit is rotated under pressure into the rock. The drilled rock enters into the barrel using circulating water as cooling agent. At intervals of 2 to 5 feet the barrel is lifted and the core is removed. The length of each core run as well as the length of the core recovered is noted.

LABORATORY WORK

%Water Contents

The natural moisture content was determined for all samples, except for those with high percentage of gravel or coarse sand.

The tests follow standards of the American Society for Testing and Materials ASTM

Designation D-2216, Latest Revision. The water or moisture content of a given soil mass is by definition the ratio of the weight of water to the oven dry weight of the soil, expressed as a percentage.

%Unconfined Compression Tests

All suitable samples of cohesive soil recovered from the split-spoon sampler were tested in unconfined compression. The ratio of the maximum load required for failure to the corrected cross sectional area of the sample expressed in tons per square foot is defined as the unconfined compressive strength.

Suelos, PSC

%Examination and Description

Soil samples are classified according to their constituents, the following terminology used to denote the approximate percentage by weight of each component.

Description Term Percent by Weight

Trace 1 - 10

Little to some 10 - 20

Sandy, silty clayey 20 - 35 and 35 - 50

The examined samples are related into one of the following main groups; boulders, gravel, sand, clay, and silt. On peat, the presence of the decomposed and partly decomposed vegetable matter, is used for identification. The differentiation between a clay and a silt is based on the presence or lack of plasticity, dilatancy and dry strength rather than on grain size. The description of the soil includes: color, odor, minerals, presence of foreign matter, geological history, etc. These descriptions as well as the results of the laboratory testing are used in grouping similar samples into a stratigraphic unit as shown on the final boring logs. Therefore, the data on subsurface exploration logs represent subsoil conditions at the precise locations of the boreholes only.

Suelos, PSC